github/workflows: split RubyDoc CI job.

This will allow syncing the documentation CI job to other repositories
with `docs` folders in Homebrew/.github#121.

.github/workflows/docs.yml

@@ -17,7 +17,7 @@ env:
   HOMEBREW_NO_INSTALL_CLEANUP: 1
 
 jobs:
-  linting:
+  docs:
     if: github.repository == 'Homebrew/brew'
     runs-on: ubuntu-22.04
     steps:
@@ -67,33 +67,3 @@ jobs:
         working-directory: ${{ steps.set-up-homebrew.outputs.repository-path }}/docs
         run: |
           bundle exec rake test
-
-  rubydoc:
-    if: github.repository == 'Homebrew/brew'
-    runs-on: ubuntu-22.04
-    env:
-      BUNDLE_GEMFILE: ${{ github.workspace }}/rubydoc/Gemfile
-    steps:
-      - name: Set up Homebrew
-        id: set-up-homebrew
-        uses: Homebrew/actions/setup-homebrew@master
-        with:
-          core: false
-          cask: false
-          test-bot: false
-
-      - name: Checkout Homebrew/rubydoc.brew.sh
-        uses: actions/checkout@v4
-        with:
-          repository: Homebrew/rubydoc.brew.sh
-          path: rubydoc
-
-      - name: Install Ruby
-        uses: ruby/setup-ruby@78c01b705fd9d5ad960d432d3a0cfa341d50e410 # v1.179.1
-        with:
-          bundler-cache: true
-          working-directory: rubydoc
-
-      - name: Process rubydoc comments
-        working-directory: ${{ steps.set-up-homebrew.outputs.repository-path }}/Library/Homebrew
-        run: bundle exec yard doc --no-output --fail-on-warning