update only changed files

.github/workflows/main.yml

@@ -117,5 +117,7 @@ jobs:
         github_token: ${{ secrets.GITHUB_TOKEN }}
         # Commits these files to gh-pages if and only if there are changes.
         publish_dir: ./build/site
+        # Update only changed files in gh-pages
+        keep_files: true
         # Insert CNAME for repository.
         cname: wiki.jmonkeyengine.org