Follows-up I301f471f86ba2.
For ease of navigation, move Converter subclasses to a group called
"Languages", which for documentation purposes is a subgroup of
"Language". The next commit does the same for Messages* files,
and Language subclasses (done separately for ease of review).
Change-Id: If1cef9aa15f536ebaedd4477ad7453426e7f3b85
The autonym "ñe'engatú", which appears in the current configuration
of translatewiki and language-names in ULS, also appears in
Ethnologue, but it is probably incorrect, as it doesn't appear
almost anywhere else.
There are several autonym variants, and the one that appears
the most consistent with the actual translations in translatewiki
is "Nhẽẽgatú".
Bug: T298385
Change-Id: I4d794dd50475c0ef17cbd906801d5a53d8446778
