[Sync EN] DTD to XML convert extensions.ent (#5697)

[github-actions]

Commit: https://github.com/php/doc-en/commit/6a1e42bcba9133ba0579636a85c77753092e1d8d
PR: https://github.com/php/doc-en/pull/5697

Archivos ES a actualizar

• extensions.ent