Code blocks should not be spaced 4 times, as this will
prevent the code from being colored. They should
also be spaced the same as the lists they are a part
of, to make reading easier.

Docs: Remove extra whitespaces in docs

See merge request gitlab-org/gitlab-ce!30493

Removes all the extra whitespaces at end of lines,
inside tags, and removes extra newlines

Centralize markdownlint configuration

See merge request gitlab-org/gitlab-ce!30263

The configuration is currently only specified in CI, by moving it into
`.mdlrc` we get immediate feedback locally in supported editors.

To ensure `mdl` is available it's also added to the `Gemfile`, though
CI will still use the version installed in the `gitlab-docs-lint` image.

Update the installation link

See merge request gitlab-org/gitlab-ce!30489

Docs: Update redirected links in docs (part 2)

See merge request gitlab-org/gitlab-ce!30441

Updating redirected links in the development, install, policy
raketasks and university dirs. Should now link to final
URL to avoid redirect hops

Move the consul server docs to its own section

Closes #63538

See merge request gitlab-org/gitlab-ce!30192