Add needs-docs workflow to fail CI (#5643)

.github/workflows/needs-docs.yml

@@ -0,0 +1,24 @@
+name: Needs Docs
+
+on:
+  pull_request:
+    types: [labeled, unlabeled]
+
+jobs:
+  check:
+    name: Check
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check for needs-docs label
+        uses: actions/github-script@v6.4.1
+        with:
+          script: |
+            const { data: labels } = await github.rest.issues.listLabelsOnIssue({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              issue_number: context.issue.number
+            });
+            const needsDocs = labels.find(label => label.name === 'needs-docs');
+            if (needsDocs) {
+              core.setFailed('Pull request needs docs');
+            }