bug#46627: [PATCH] Add new help command 'describe-command'

[Eli Zaretskii]

> From: Richard Stallman <rms@gnu.org>
> Cc: eliz@gnu.org, larsi@gnus.org, 46627@debbugs.gnu.org
> Date: Sat, 20 Feb 2021 11:06:07 -0500
> 
> There seems to be little difference between the proposed
> describe-command command and the existing describe-function command.
> Whatever the former could do, the latter already does.

The main difference is in the completion these commands offer.
describe-command completes only on commands.