Add change record re removal of hook_locale

[klonos]

This came up in #4838 (comment) but I see no change record for it.

For reference: https://api.drupal.org/api/drupal/modules%21locale%21locale.api.php/function/hook_locale/7.x

[indigoxela]

FTR Backdrop has no change record for this yet, because we inherited the change from early D8:
https://www.drupal.org/node/1266462 - "hook_locale() has been removed with no replacement."

[klonos]

Thanks for digging that up @indigoxela 👍 ...even a copy-paste of that D8 change record would suffice I believe.