build the docs for master (#10323)

.github/workflows/docs.yaml

@@ -7,6 +7,8 @@ on:
       - develop
       # For documentation specific to a release
       - 'release-v*'
+      # stable docs
+      - master
 
   workflow_dispatch:
 
@@ -25,40 +27,35 @@ jobs:
       - name: Build the documentation
         run: mdbook build
 
-      # Deploy to the latest documentation directories
-      - name: Deploy latest documentation
-        uses: peaceiris/actions-gh-pages@068dc23d9710f1ba62e86896f84735d869951305 # v3.8.0
-        with:
-          github_token: ${{ secrets.GITHUB_TOKEN }}
-          keep_files: true
-          publish_dir: ./book
-          destination_dir: ./develop
-
-      - name: Get the current Synapse version
+      # Figure out the target directory.
+      #
+      # The target directory depends on the name of the branch
+      #
+      - name: Get the target directory name
         id: vars
-        # The $GITHUB_REF value for a branch looks like `refs/heads/release-v1.2`. We do some
-        # shell magic to remove the "refs/heads/release-v" bit from this, to end up with "1.2",
-        # our major/minor version number, and set this to a var called `branch-version`.
-        #
-        # We then use some python to get Synapse's full version string, which may look
-        # like "1.2.3rc4". We set this to a var called `synapse-version`. We use this
-        # to determine if this release is still an RC, and if so block deployment.
         run: |
-          echo ::set-output name=branch-version::${GITHUB_REF#refs/heads/release-v}
-          echo ::set-output name=synapse-version::`python3 -c 'import synapse; print(synapse.__version__)'`
-
-      # Deploy to the version-specific directory
-      - name: Deploy release-specific documentation
-        # We only carry out this step if we're running on a release branch,
-        # and the current Synapse version does not have "rc" in the name.
-        #
-        # The result is that only full releases are deployed, but can be
-        # updated if the release branch gets retroactive fixes.
-        if: ${{ startsWith( github.ref, 'refs/heads/release-v' ) && !contains( steps.vars.outputs.synapse-version, 'rc') }}
-        uses: peaceiris/actions-gh-pages@v3
+          # first strip the 'refs/heads/' prefix with some shell foo
+          branch="${GITHUB_REF#refs/heads/}"
+
+          case $branch in
+              release-*)
+                  # strip 'release-' from the name for release branches.
+                  branch="${branch#release-}"
+                  ;;
+              master)
+                  # deploy to "latest" for the master branch.
+                  branch="latest"
+                  ;;
+          esac
+
+          # finally, set the 'branch-version' var.
+          echo "::set-output name=branch-version::$branch"
+          
+      # Deploy to the target directory.
+      - name: Deploy to gh pages
+        uses: peaceiris/actions-gh-pages@068dc23d9710f1ba62e86896f84735d869951305 # v3.8.0
         with:
           github_token: ${{ secrets.GITHUB_TOKEN }}
           keep_files: true
           publish_dir: ./book
-          # The resulting documentation will end up in a directory named `vX.Y`.
-          destination_dir: ./v${{ steps.vars.outputs.branch-version }}
+          destination_dir: ./${{ steps.vars.outputs.branch-version }}