Pulsar Go client docs (apache#1838)

* add new doc and add new doc to sidebar index

* add section on client instantiation

* begin adding consumer and reader section

* begin adding consumer options table

* add section on building messages

* add more example code for producers and consumers

* finish draft of go client docs

* update reader definition for popovers

* fix typo in reader definition

* add missing license header

* Updated to go docs

site/_data/popovers.yaml

@@ -92,6 +92,10 @@ pulsar:
 pulsar-functions:
   q: What are Pulsar Functions?
   def: Pulsar Functions are lightweight functions that can consume messages from Pulsar topics, apply custom processing logic, and, if desired, publish results to topics.
+reader:
+  q: What is a Pulsar reader?
+  def: |
+    "Pulsar readers are message processors much like Pulsar consumers but with two crucial differences: (1) you can specify *where* on a topic readers begin processing messages (consumers always begin with the latest available unacked message); and (2) readers don't retain data or acknowledge messages."
 retention-policy:
   q: What is a retention policy?
   def: Size and/or time limits that you can set on a namespace to configure retention of messages that have already been acknowledged.

site/_data/sidebar.yaml

@@ -92,10 +92,12 @@ groups:
   docs:
   - title: Java client
     endpoint: Java
-  - title: C++ client
-    endpoint: Cpp
+  - title: Go client
+    endpoint: go
   - title: Python client
     endpoint: Python
+  - title: C++ client
+    endpoint: Cpp
   - title: WebSocket API
     endpoint: WebSocket
 

site/docs/latest/admin/Authz.md

@@ -53,13 +53,13 @@ The first step is to create the certificate for the CA. The CA will be used to s
 
 ###### Linux
 
-```shell
+```bash
 $ CA.pl -newca
 ```
 
-###### MacOS
+###### macOS
 
-```
+```bash
 $ /System/Library/OpenSSL/misc/CA.pl -newca
 ```