Adds a note to the README section for time it takes for Middleman
to render the www-gitlab-com.

This makes it easier to debug a single page, especially when it fails to
build.

This reverts merge request !14021

Various changes:

- Some KRs for Geo added.
- Use blockquotes in Critical acclaim
- Advise to use format `Owner:` to define a Key Result that is
  countable per Owner (each Owner should have max 9 KRs)

[ci skip]

[ci skip]

After the handbook was split into smaller pages by https://gitlab.com/gitlab-com/www-gitlab-com/merge_requests/4939 many of the old links needed updating

Updated applications page