Update Githubpages version (facebook#9670)

Summary:
According to https://pages.github.com/versions/, bump the version from 209 to
225 to address https://github.com/facebook/rocksdb/security/dependabot/2

Pull Request resolved: facebook#9670

Test Plan:
```
cd docs && bundle check
```

Reviewed By: ajkr

Differential Revision: D34690813

Pulled By: riversand963

fbshipit-source-id: c9b5fb8a5e3f2a176672480bcb4068befa3e2158

docs/Gemfile

@@ -1,4 +1,4 @@
 source 'https://rubygems.org'
-gem 'github-pages', '~> 209'
+gem 'github-pages', '~> 225'
 
 gem "webrick", "~> 1.7"

docs/Gemfile.lock

@@ -1,7 +1,7 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    activesupport (6.0.3.4)
+    activesupport (6.0.4.6)
       concurrent-ruby (~> 1.0, >= 1.0.2)
       i18n (>= 0.7, < 2)
       minitest (~> 5.1)
@@ -14,80 +14,98 @@ GEM
       execjs
     coffee-script-source (1.11.1)
     colorator (1.1.0)
-    commonmarker (0.17.13)
-      ruby-enum (~> 0.5)
-    concurrent-ruby (1.1.7)
-    dnsruby (1.61.5)
+    commonmarker (0.23.4)
+    concurrent-ruby (1.1.9)
+    dnsruby (1.61.9)
       simpleidn (~> 0.1)
-    em-websocket (0.5.2)
+    em-websocket (0.5.3)
       eventmachine (>= 0.12.9)
-      http_parser.rb (~> 0.6.0)
-    ethon (0.12.0)
-      ffi (>= 1.3.0)
+      http_parser.rb (~> 0)
+    ethon (0.15.0)
+      ffi (>= 1.15.0)
     eventmachine (1.2.7)
-    execjs (2.7.0)
-    faraday (1.3.0)
+    execjs (2.8.1)
+    faraday (1.10.0)
+      faraday-em_http (~> 1.0)
+      faraday-em_synchrony (~> 1.0)
+      faraday-excon (~> 1.1)
+      faraday-httpclient (~> 1.0)
+      faraday-multipart (~> 1.0)
       faraday-net_http (~> 1.0)
+      faraday-net_http_persistent (~> 1.0)
+      faraday-patron (~> 1.0)
+      faraday-rack (~> 1.0)
+      faraday-retry (~> 1.0)
+      ruby2_keywords (>= 0.0.4)
+    faraday-em_http (1.0.0)
+    faraday-em_synchrony (1.0.0)
+    faraday-excon (1.1.0)
+    faraday-httpclient (1.0.1)
+    faraday-multipart (1.0.3)
       multipart-post (>= 1.2, < 3)
-      ruby2_keywords
-    faraday-net_http (1.0.0)
-    ffi (1.14.2)
+    faraday-net_http (1.0.1)
+    faraday-net_http_persistent (1.2.0)
+    faraday-patron (1.0.0)
+    faraday-rack (1.0.0)
+    faraday-retry (1.0.3)
+    ffi (1.15.5)
     forwardable-extended (2.6.0)
     gemoji (3.0.1)
-    github-pages (209)
-      github-pages-health-check (= 1.16.1)
+    github-pages (225)
+      github-pages-health-check (= 1.17.9)
       jekyll (= 3.9.0)
       jekyll-avatar (= 0.7.0)
       jekyll-coffeescript (= 1.1.1)
-      jekyll-commonmark-ghpages (= 0.1.6)
+      jekyll-commonmark-ghpages (= 0.2.0)
       jekyll-default-layout (= 0.1.4)
       jekyll-feed (= 0.15.1)
       jekyll-gist (= 1.5.0)
       jekyll-github-metadata (= 2.13.0)
+      jekyll-include-cache (= 0.2.1)
       jekyll-mentions (= 1.6.0)
       jekyll-optional-front-matter (= 0.3.2)
       jekyll-paginate (= 1.1.0)
       jekyll-readme-index (= 0.3.0)
       jekyll-redirect-from (= 0.16.0)
       jekyll-relative-links (= 0.6.1)
-      jekyll-remote-theme (= 0.4.2)
+      jekyll-remote-theme (= 0.4.3)
       jekyll-sass-converter (= 1.5.2)
-      jekyll-seo-tag (= 2.6.1)
+      jekyll-seo-tag (= 2.8.0)
       jekyll-sitemap (= 1.4.0)
       jekyll-swiss (= 1.0.0)
-      jekyll-theme-architect (= 0.1.1)
-      jekyll-theme-cayman (= 0.1.1)
-      jekyll-theme-dinky (= 0.1.1)
-      jekyll-theme-hacker (= 0.1.2)
-      jekyll-theme-leap-day (= 0.1.1)
-      jekyll-theme-merlot (= 0.1.1)
-      jekyll-theme-midnight (= 0.1.1)
-      jekyll-theme-minimal (= 0.1.1)
-      jekyll-theme-modernist (= 0.1.1)
-      jekyll-theme-primer (= 0.5.4)
-      jekyll-theme-slate (= 0.1.1)
-      jekyll-theme-tactile (= 0.1.1)
-      jekyll-theme-time-machine (= 0.1.1)
+      jekyll-theme-architect (= 0.2.0)
+      jekyll-theme-cayman (= 0.2.0)
+      jekyll-theme-dinky (= 0.2.0)
+      jekyll-theme-hacker (= 0.2.0)
+      jekyll-theme-leap-day (= 0.2.0)
+      jekyll-theme-merlot (= 0.2.0)
+      jekyll-theme-midnight (= 0.2.0)
+      jekyll-theme-minimal (= 0.2.0)
+      jekyll-theme-modernist (= 0.2.0)
+      jekyll-theme-primer (= 0.6.0)
+      jekyll-theme-slate (= 0.2.0)
+      jekyll-theme-tactile (= 0.2.0)
+      jekyll-theme-time-machine (= 0.2.0)
       jekyll-titles-from-headings (= 0.5.3)
       jemoji (= 0.12.0)
       kramdown (= 2.3.1)
       kramdown-parser-gfm (= 1.1.0)
       liquid (= 4.0.3)
       mercenary (~> 0.3)
       minima (= 2.5.1)
-      nokogiri (>= 1.10.4, < 2.0)
-      rouge (= 3.23.0)
+      nokogiri (>= 1.12.5, < 2.0)
+      rouge (= 3.26.0)
       terminal-table (~> 1.4)
-    github-pages-health-check (1.16.1)
+    github-pages-health-check (1.17.9)
       addressable (~> 2.3)
       dnsruby (~> 1.60)
       octokit (~> 4.0)
-      public_suffix (~> 3.0)
+      public_suffix (>= 3.0, < 5.0)
       typhoeus (~> 1.3)
     html-pipeline (2.14.0)
       activesupport (>= 2)
       nokogiri (>= 1.4)
-    http_parser.rb (0.6.0)
+    http_parser.rb (0.8.0)
     i18n (0.9.5)
       concurrent-ruby (~> 1.0)
     jekyll (3.9.0)
@@ -108,12 +126,12 @@ GEM
     jekyll-coffeescript (1.1.1)
       coffee-script (~> 2.2)
       coffee-script-source (~> 1.11.1)
-    jekyll-commonmark (1.3.1)
-      commonmarker (~> 0.14)
-      jekyll (>= 3.7, < 5.0)
-    jekyll-commonmark-ghpages (0.1.6)
-      commonmarker (~> 0.17.6)
-      jekyll-commonmark (~> 1.2)
+    jekyll-commonmark (1.4.0)
+      commonmarker (~> 0.22)
+    jekyll-commonmark-ghpages (0.2.0)
+      commonmarker (~> 0.23.4)
+      jekyll (~> 3.9.0)
+      jekyll-commonmark (~> 1.4.0)
       rouge (>= 2.0, < 4.0)
     jekyll-default-layout (0.1.4)
       jekyll (~> 3.0)
@@ -124,6 +142,8 @@ GEM
     jekyll-github-metadata (2.13.0)
       jekyll (>= 3.4, < 5.0)
       octokit (~> 4.0, != 4.4.0)
+    jekyll-include-cache (0.2.1)
+      jekyll (>= 3.7, < 5.0)
     jekyll-mentions (1.6.0)
       html-pipeline (~> 2.3)
       jekyll (>= 3.7, < 5.0)
@@ -136,57 +156,57 @@ GEM
       jekyll (>= 3.3, < 5.0)
     jekyll-relative-links (0.6.1)
       jekyll (>= 3.3, < 5.0)
-    jekyll-remote-theme (0.4.2)
+    jekyll-remote-theme (0.4.3)
       addressable (~> 2.0)
       jekyll (>= 3.5, < 5.0)
       jekyll-sass-converter (>= 1.0, <= 3.0.0, != 2.0.0)
       rubyzip (>= 1.3.0, < 3.0)
     jekyll-sass-converter (1.5.2)
       sass (~> 3.4)
-    jekyll-seo-tag (2.6.1)
-      jekyll (>= 3.3, < 5.0)
+    jekyll-seo-tag (2.8.0)
+      jekyll (>= 3.8, < 5.0)
     jekyll-sitemap (1.4.0)
       jekyll (>= 3.7, < 5.0)
     jekyll-swiss (1.0.0)
-    jekyll-theme-architect (0.1.1)
-      jekyll (~> 3.5)
+    jekyll-theme-architect (0.2.0)
+      jekyll (> 3.5, < 5.0)
       jekyll-seo-tag (~> 2.0)
-    jekyll-theme-cayman (0.1.1)
-      jekyll (~> 3.5)
+    jekyll-theme-cayman (0.2.0)
+      jekyll (> 3.5, < 5.0)
       jekyll-seo-tag (~> 2.0)
-    jekyll-theme-dinky (0.1.1)
-      jekyll (~> 3.5)
+    jekyll-theme-dinky (0.2.0)
+      jekyll (> 3.5, < 5.0)
       jekyll-seo-tag (~> 2.0)
-    jekyll-theme-hacker (0.1.2)
+    jekyll-theme-hacker (0.2.0)
       jekyll (> 3.5, < 5.0)
       jekyll-seo-tag (~> 2.0)
-    jekyll-theme-leap-day (0.1.1)
-      jekyll (~> 3.5)
+    jekyll-theme-leap-day (0.2.0)
+      jekyll (> 3.5, < 5.0)
       jekyll-seo-tag (~> 2.0)
-    jekyll-theme-merlot (0.1.1)
-      jekyll (~> 3.5)
+    jekyll-theme-merlot (0.2.0)
+      jekyll (> 3.5, < 5.0)
       jekyll-seo-tag (~> 2.0)
-    jekyll-theme-midnight (0.1.1)
-      jekyll (~> 3.5)
+    jekyll-theme-midnight (0.2.0)
+      jekyll (> 3.5, < 5.0)
       jekyll-seo-tag (~> 2.0)
-    jekyll-theme-minimal (0.1.1)
-      jekyll (~> 3.5)
+    jekyll-theme-minimal (0.2.0)
+      jekyll (> 3.5, < 5.0)
       jekyll-seo-tag (~> 2.0)
-    jekyll-theme-modernist (0.1.1)
-      jekyll (~> 3.5)
+    jekyll-theme-modernist (0.2.0)
+      jekyll (> 3.5, < 5.0)
       jekyll-seo-tag (~> 2.0)
-    jekyll-theme-primer (0.5.4)
+    jekyll-theme-primer (0.6.0)
       jekyll (> 3.5, < 5.0)
       jekyll-github-metadata (~> 2.9)
       jekyll-seo-tag (~> 2.0)
-    jekyll-theme-slate (0.1.1)
-      jekyll (~> 3.5)
+    jekyll-theme-slate (0.2.0)
+      jekyll (> 3.5, < 5.0)
       jekyll-seo-tag (~> 2.0)
-    jekyll-theme-tactile (0.1.1)
-      jekyll (~> 3.5)
+    jekyll-theme-tactile (0.2.0)
+      jekyll (> 3.5, < 5.0)
       jekyll-seo-tag (~> 2.0)
-    jekyll-theme-time-machine (0.1.1)
-      jekyll (~> 3.5)
+    jekyll-theme-time-machine (0.2.0)
+      jekyll (> 3.5, < 5.0)
       jekyll-seo-tag (~> 2.0)
     jekyll-titles-from-headings (0.5.3)
       jekyll (>= 3.3, < 5.0)
@@ -201,7 +221,7 @@ GEM
     kramdown-parser-gfm (1.1.0)
       kramdown (~> 2.0)
     liquid (4.0.3)
-    listen (3.4.0)
+    listen (3.7.1)
       rb-fsevent (~> 0.10, >= 0.10.3)
       rb-inotify (~> 0.9, >= 0.9.10)
     mercenary (0.3.6)
@@ -210,27 +230,25 @@ GEM
       jekyll (>= 3.5, < 5.0)
       jekyll-feed (~> 0.9)
       jekyll-seo-tag (~> 2.1)
-    minitest (5.14.3)
+    minitest (5.15.0)
     multipart-post (2.1.1)
     nokogiri (1.13.3)
       mini_portile2 (~> 2.8.0)
       racc (~> 1.4)
-    octokit (4.20.0)
+    octokit (4.22.0)
       faraday (>= 0.9)
       sawyer (~> 0.8.0, >= 0.5.3)
     pathutil (0.16.2)
       forwardable-extended (~> 2.6)
-    public_suffix (3.1.1)
+    public_suffix (4.0.6)
     racc (1.6.0)
-    rb-fsevent (0.10.4)
+    rb-fsevent (0.11.1)
     rb-inotify (0.10.1)
       ffi (~> 1.0)
     rexml (3.2.5)
-    rouge (3.23.0)
-    ruby-enum (0.8.0)
-      i18n
-    ruby2_keywords (0.0.2)
-    rubyzip (2.3.0)
+    rouge (3.26.0)
+    ruby2_keywords (0.0.5)
+    rubyzip (2.3.2)
     safe_yaml (1.0.5)
     sass (3.7.4)
       sass-listen (~> 4.0.0)
@@ -240,7 +258,7 @@ GEM
     sawyer (0.8.2)
       addressable (>= 2.3.5)
       faraday (> 0.8, < 2.0)
-    simpleidn (0.1.1)
+    simpleidn (0.2.1)
       unf (~> 0.1.4)
     terminal-table (1.8.0)
       unicode-display_width (~> 1.1, >= 1.1.1)
@@ -251,16 +269,16 @@ GEM
       thread_safe (~> 0.1)
     unf (0.1.4)
       unf_ext
-    unf_ext (0.0.7.7)
-    unicode-display_width (1.7.0)
+    unf_ext (0.0.8)
+    unicode-display_width (1.8.0)
     webrick (1.7.0)
-    zeitwerk (2.4.2)
+    zeitwerk (2.5.4)
 
 PLATFORMS
   ruby
 
 DEPENDENCIES
-  github-pages (~> 209)
+  github-pages (~> 225)
   webrick (~> 1.7)
 
 BUNDLED WITH