[Sync EN] Use &true;/&false;/&null; entities for boolean/null constants (#5641)

[github-actions]

Commit: https://github.com/php/doc-en/commit/911fe79de766ef4475bf22446903667a0f3a24d3
PR: https://github.com/php/doc-en/pull/5641

Archivos ES a actualizar

• language/control-structures/include.xml
• language/enumerations.xml
• language/oop5/overloading.xml
• language/predefined/weakreference.xml
• language/types/array.xml
• language/types/declarations.xml
• reference/datetime/dateinterval/createfromdatestring.xml
• reference/datetime/datetime/modify.xml
• reference/datetime/datetimeimmutable/modify.xml
• reference/filter/constants.xml
• reference/info/functions/ini-get.xml
• reference/intl/ini.xml
• reference/mbstring/functions/mb-strcut.xml
• reference/mbstring/functions/mb-substr.xml
• reference/pdo/constants.fetch-modes.xml
• reference/pdo/pdo/getattribute.xml
• reference/reflection/reflectionenum/getbackingtype.xml
• reference/swoole/swoole/coroutine/lock/lock.xml
• reference/swoole/swoole/coroutine/lock/trylock.xml
• reference/swoole/swoole/coroutine/lock/unlock.xml
• reference/win32service/rightinfo/get-full-username.xml