[Sync EN] Add security warning about publicly exposed PHP-FPM (#5263)

[github-actions]

Commit: https://github.com/php/doc-en/commit/7efe863bc4b65788f652e3d9eff27941b1a74540
PR: https://github.com/php/doc-en/pull/5263

Archivos ES a actualizar

• install/fpm/configuration.xml
• install/fpm/index.xml