bug#39553: 28.0.50; ada mode was removed

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Date: Mon, 07 Sep 2020 22:56:42 +0200
> Cc: 39553@debbugs.gnu.org
> 
> As for the policy of moving modes to ELPA -- I think we shouldn't do
> that until we have the "include ELPA in the Emacs distribution" thing
> that's been discussed for quite a while (but hasn't been implemented
> yet).

I tend to agree.