These are all over the place, but several are of interest to the
Chief of Staff team.

More link fixes, focusing on URLs that match the substring
about.gitlab.com/handbook/product

We link to the product section of our handbook a LOT. This MR updates
some of the product links in the handbook to point to the new site.

Scoping down to a subdirectory should help us move these through
more quickly. Or, at least, do more sensible levels of search-and-
replace.

We see that the checklist is not always ticked. Those acceptance
guidelines are very important for newer contributors, but are
reviewed by experienced ones only from time to time.

Ticking the checklist does not necessarily ensure that all
the guidelines are followed. Rewording this point let us
make sure the content of the checklist is more important
that the formality of checking it.

This is not used on the current docs website
and needs to be removed for future compatibility
with Hugo.

Because any maintainer can merge
Related to: https://gitlab.com/gitlab-org/gitlab/-/issues/397788

Because we're changing how we
update pages in this folder

Because we changed the way we
do the markdown.

Related to: https://gitlab.com/gitlab-org/gitlab-docs/-/issues/1690

Break apart into unordered list items
Hard line wraps
Add commas

Because right now we provide the
same information in many places
and we should try to standardize
on one location, SSoT.

Related to: https://gitlab.com/gitlab-org/technical-writing/-/issues/744

Related to: https://gitlab.com/gitlab-org/technical-writing/-/issues/744

Because they were duplicated

Related to: https://gitlab.com/gitlab-org/technical-writing/-/issues/744

Because we have a standard of
"For more information, see..."

Because they are on the other pages
as well as the handbook.
Related to: https://gitlab.com/gitlab-org/technical-writing/-/issues/744

Old link was to a hard-coded link that redirected users to a new url.

New link uses relative path that works in compiled documentation.

merge_request_application_and_rate_limit_guidelines.md becomes
rate_limits.md in a subdirectory.

As part of reuniting pages related to merge requests together in a
single subdirectory, let's start by shifting the page and giving it
a MERCIFULLY SHORTER filename.

Bring this statement closer to GitLab tone
and style.

Related epic: https://gitlab.com/groups/gitlab-com/-/epics/1940

- Update templates
- Update occurences of contributing/#breaking-changes

The TW team has to clean up stray whitespace every month,
so we should have a vale rule to gently warn people
when they are introducing EOL whitespace