**Feature summary** (what you would like to be able to do and where):
Support apc and ajp language codes.
**Use case(s)** (list the steps that you performed to discover that problem, and describe the actual underlying problem which you want to solve. Do not describe only a solution):
I want to be able to use `language=ajp` (for instance) in citation templates on the English Wikipedia.
However, there is a limited number of supported languages for citation on Wikipedia: https://en.wikipedia.org/wiki/Template:Citation_Style_documentation/language/doc
In particular, some Arabic varieties such as ajp (South Levantine) and apc (North Levantine) are not recognized whereas others such as arz (Egyptian), arq (Algerian), aeb (Tunisian), shu (Chadian), and ary (Moroccan) are: https://en.wikipedia.org/wiki/Help_talk:Citation_Style_1#Add_languages
**Benefits** (why should this be implemented?):
Support one of the most spoken and most widely understood Arabic varieties in the Arab world.
According to {T187344}; "If one or the other language code is needed (for labels/descriptions/aliases) or just monolingual string or lexemes, it might be worth creating a separate request.", here it is!
See also: {T286290} & {T286417}
Adding languages: https://www.mediawiki.org/wiki/Manual:Adding_and_removing_languages
[x] Add to translatewiki
[ ] Add to cldr extension if possible or the cldr overrides
[ ] Add to language-data if not possible to add to cldr extension
[ ] Add to `includes/languages/data/Names.php`
[ ] Set fallback etc
[ ] Add to jquery.ime
[ ] Add to rtl languages of MF
[ ] Add to release notes