help: add :config-doc:`section.key` shorthand to insert documentation
The config items defined in the configitems.toml file can already hold their
documentation. Having some way to automatically insert it was a long standing
low hanging fruit. So I did a first implementation on that. It fairly simple,
but it open the door to more.
It will be used in the next changeset.
# So GitLab doesn't think we're using tons of Perl
*.t -linguist-detectable