Add generate-changelog job

.github/workflows/generate-changelog.yml

@@ -0,0 +1,32 @@
+name: Generate CHANGELOG
+on:
+  pull_request_target:
+    types: [closed]
+  workflow_run:
+    workflows: [Generate registry documentation]
+    types:
+      - completed
+  workflow_dispatch:
+jobs:
+  generate-changelog:
+    if: github.event.pull_request.merged || github.event_name == 'workflow_dispatch'
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+      - run: cd tools && go install github.com/hashicorp/go-changelog/cmd/changelog-build
+      - run: ./scripts/generate-changelog.sh
+      - run: |
+          if [[ `git status --porcelain` ]]; then
+            if ${{github.event_name == 'workflow_dispatch'}}; then
+              MSG="Update CHANGELOG.md (Manual Trigger)"
+            else
+              MSG="Update CHANGELOG.md for #${{ github.event.pull_request.number }}"
+            fi
+            git config --local user.email changelogbot@cloudflare.com
+            git config --local user.name changelogbot
+            git add CHANGELOG.md
+            git commit -m "$MSG"
+            git push
+          fi