[Sync EN] Correctly format predefined constant pages

PR: `https://github.com/php/doc-en/pull/5444` (2026-04-27)

**Archivos ES a actualizar**
- `appendices/reserved.constants.core.xml`
- `appendices/tokens.xml`
- `reference/dir/constants.xml`
- `reference/iconv/constants.xml`
- `reference/mysqli/constants.xml`
- `reference/openssl/constants.xml`

