Replace MR Description Format links
What does this MR do?
Replace links to the Merge request description format section with
up-to-date instructions on using the MR template built into the UI.
The Merge request description format section was removed in 2f7e28d1,
but links were left in the table of contents and in the MR description
instructions. Presumably, the section was removed because MR templates
are now provided by the GitLab UI.
Moving docs to a new location?
No.
