Add documentation for sysctl security requirement

Co-authored-by: jonrohan <[email protected]>

Author: Copilot

.github/workflows/nodejs.yml

@@ -9,6 +9,9 @@ jobs:
       uses: actions/setup-node@v4
       with:
         node-version: '20.x'
+    # Enable unprivileged user namespaces for Chrome sandbox
+    # This is required because Ubuntu 23.10+ disables them by default
+    # See: https://github.com/actions/runner-images/issues/9621
     - name: Enable user namespaces
       run: sudo sysctl -w kernel.unprivileged_userns_clone=1
     - run: npm install