Roll documentation linting dependencies forward

What does this MR do and why?

For #719, let's rolls documentation linting versions in the project forward before building a container image with them that we can use in other projects.

The newer version of markdownlint-cli2 required minor formatting changes to the configuration file and turning on more rumdl rules required limiting the scope of the check to just doc, which was the original intent.

How to set up and validate locally

1. Configure a local GitLab Docs environment.
2. Check out this branch.
3. Run make setup.
4. Run make lint-markdown.

Merge request acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this merge request.
• If this MR changes how markdown is interpreted, share this MR in the #tech-docs-localization slack channel. The translation tooling might need to be updated, for example if new syntax is added or existing syntax rendering is changed.