A few thoughts

• the rlimit settings are not inherently mock settings, they apply to all of kojid. They should go in their own section (and this should be where the _rlimits_kojid label points). It's definitely worth remarking and linking in the mock section though.
• let's reserve the mock.rst filename for some future top mock doc. This is specifically about mock configuration, so maybe mock_config.rst or similar.
• server_howto could benefit from a link to the mock config doc right next to the link to the kojid conf doc.

updates here https://pagure.io/fork/mikem/koji/commits/pr4025updates

Commit 91f410f8 fixes this pull-request

added to PR