Update book deploy CI to separete latest and tags. (FuelLabs#47)

.github/workflows/gh-pages.yml

@@ -4,6 +4,8 @@ on:
   push:
     branches:
       - master
+    tags:
+      - v*
 
 jobs:
   deploy:
@@ -18,8 +20,24 @@ jobs:
 
       - run: mdbook build docs
 
-      - name: Deploy
+      - name: Deploy latest
         uses: peaceiris/actions-gh-pages@v3
         with:
           github_token: ${{ secrets.GITHUB_TOKEN }}
           publish_dir: ./docs/book
+          destination_dir: latest
+        if: github.ref == 'refs/heads/master'
+
+      - name: Get tag
+        id: branch_name
+        run: |
+          echo ::set-output name=BRANCH_NAME::${GITHUB_REF#refs/tags/}
+        if: startsWith(github.ref, 'refs/tags')
+
+      - name: Deploy tag
+        uses: peaceiris/actions-gh-pages@v3
+        with:
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+          publish_dir: ./docs/book
+          destination_dir: ${{ steps.branch_name.outputs.BRANCH_NAME }}
+        if: startsWith(github.ref, 'refs/tags')