Add documentation releated build and checks to GitHub workflows

There's nothing in the pull request verification that checks if
the command-line references are up-to-date. Add a job to the pull
request update workflow that verifies this.

There's nothing in the release build workflow that generates the
documentation and uploads the documentation artifacts so that they
can be published. Add a step to the build release job that generates
the documentation so that it can be published to swift.org.

Author: cmcgee1024

.github/workflows/build_release.yml

@@ -23,10 +23,17 @@ jobs:
     steps:
       - name: Checkout repository
         uses: actions/checkout@v4
-      - name: Build Artifact
+      - name: Build Release Artifact
         run: swift run build-swiftly-release ${{ inputs.skip }} ${{ inputs.version }}
-      - name: Upload Artifact
+      - name: Upload Release Artifact
         uses: actions/upload-artifact@v4
         with:
           path: .build/release/swiftly-*.tar.gz
           if-no-files-found: error
+      - name: Build Documentation Artifacts
+        run: swift package --allow-writing-to-directory .build/docs generate-documentation --target SwiftlyDocs --output-path .build/docs
+      - name: Upload Documentation Artifacts
+        uses: actions/upload-artifact@v4
+        with:
+          path: .build/docs/**
+          if-no-files-found: error

.github/workflows/pull_request.yml

@@ -57,3 +57,24 @@ jobs:
       linux_pre_build_command: ./scripts/prep-gh-action.sh
       linux_build_command: swift run swiftformat --lint --dryrun .
       enable_windows_checks: false
+
+  docscheck:
+    name: Documentation Check
+    runs-on: ubuntu-latest
+    container:
+      image: "swift:6.0-noble"
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+      - name: Prepare the action
+        run: ./scripts/prep-gh-action.sh && ./scripts/install-libarchive.sh
+      - name: Generate Swiftly CLI Reference and Check for Differences
+        run: swift package plugin --allow-writing-to-package-directory generate-docs-reference && git diff-index --quiet HEAD --  || (echo "The documentation hasn't been updated with the latest swiftly command-line reference. Please run 'swift package plugin generate-docs-reference' and commit/push the changes."; exit 1)
+      - name: Generate Documentation Set
+        run: swift package --allow-writing-to-directory .build/docs generate-documentation --target SwiftlyDocs --output-path .build/docs
+      - name: Upload Documentation Artifacts
+        uses: actions/upload-artifact@v4
+        with:
+          path: .build/docs/**
+          if-no-files-found: error
+          retention-days: 1