Merge request for documentation

[Knute Snortum]

On the LilyPond users' list, I proposed some changes to the
documentation.  It was suggested that I submit a merge request for
this change, but I'm having a tough time doing that because when I try
to push to my fork, I get a permissions error.  What have I done
wrong?

----- begin command line output
$ git remote -v
fork git@gitlab.com:ksnortum/lilypond.git (fetch)
fork git@gitlab.com:ksnortum/lilypond.git (push)
origin https://gitlab.com/lilypond/lilypond.git (fetch)
origin https://gitlab.com/lilypond/lilypond.git (push)

$ git push fork dev/doc-accidental
git@gitlab.com: Permission denied (publickey,keyboard-interactive).
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.
----- end command line output

--
Knute Snortum