[Sync EN] ext/simplexml: Document that get methods and string casts no longer implicitly rewind (#5737)

[github-actions]

Commit: https://github.com/php/doc-en/commit/418ec505128707215c5c99ad4a66a88bfd84a0ff
PR: https://github.com/php/doc-en/pull/5737

Archivos ES a actualizar

• reference/simplexml/simplexmlelement.xml
• reference/simplexml/simplexmlelement/rewind.xml