[Github] Add clang-tools-extra docs to CI (#69827)

This patch adds the clang-tools-extra docs to the Github CI job that
builds docs, enabling the ability to easily ensure the docs build
properly without warnings in PRs and at the tip of tree.

Author: boomanaiden154

.github/workflows/docs.yml

@@ -15,10 +15,12 @@ on:
     paths:
       - 'llvm/docs/**'
       - 'clang/docs/**'
+      - 'clang-tools-extra/docs/**'
   pull_request:
     paths:
       - 'llvm/docs/**'
       - 'clang/docs/**'
+      - 'clang-tools-extra/docs/**'
 
 jobs:
   check-docs-build:
@@ -47,6 +49,8 @@ jobs:
               - 'llvm/docs/**'
             clang:
               - 'clang/docs/**'
+            clang-tools-extra:
+              - 'clang-tools-extra/docs/**'
       - name: Setup Python env
         uses: actions/setup-python@v4
         with:
@@ -69,4 +73,9 @@ jobs:
         run: |
           cmake -B clang-build -GNinja -DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_PROJECTS="clang" -DLLVM_ENABLE_SPHINX=ON ./llvm
           TZ=UTC ninja -C clang-build docs-clang-html docs-clang-man
+      - name: Build clang-tools-extra docs
+        if: steps.docs-changed-subprojects.outputs.clang-tools-extra_any_changed == 'true'
+        run: |
+          cmake -B clang-tools-extra-build -GNinja -DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_PROJECTS="clang;clang-tools-extra" -DLLVM_ENABLE_SPHINX=ON ./llvm
+          TZ=UTC ninja -C clang-tools-extra-build docs-clang-tools-html docs-clang-tools-man