[TASK] Remove outdated version specific hint (#5871)

Releases: main, 13.4

Author: linawolf

Documentation/ApiOverview/Localization/XliffFormat.rst

@@ -64,9 +64,6 @@ available in :file:`de_CH.locallang.xlf`, and then automatically falls back to
 the non-region-specific "de" label file :file:`de.locallang.xlf` without any
 further configuration to TYPO3.
 
-Before TYPO3 v12.2, one has to define a
-:ref:`custom language <xliff-translating-languages>`.
-
 ..  note::
     The original file must always be in English, so it is not allowed to create
     a file with the prefix "en", for example :file:`en.locallang.xlf`.