The N'Ko Wikipedia (nqo) was created in September. It still doesn't appear in the iOS Wikipedia app.
You cannot find it on the main page, or in the interanguage links list on the Martin Luther King Jr. article, even though they are linked through Wikidata.
It may affect more wikis that were created recently, such as Mon (mnw) and Sakizaya (szy), but I don't have an iOS device myself, and till now I've only received complaints from N'Ko.
In any case, the documentation of the necessary steps to add a language to the iOS app should be documented at https://wikitech.wikimedia.org/wiki/Add_a_wiki . It looks like the documentation at the moment is incomplete.