Add markdown linter for runbooks

[machadovilaca]

What this PR does / why we need it:

Adds markdown linter for runbooks with same rules and openshift/runbooks

jira-ticket: https://issues.redhat.com/browse/CNV-40900

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

Special notes for your reviewer:

Checklist

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• Design: A design document was considered and is present (link) or not required
• PR: The PR description is expressive enough and will help future contributors
• Code: Write code that humans can understand and Keep it simple
• Refactor: You have left the code cleaner than you found it (Boy Scout Rule)
• Upgrade: Impact of this change on upgrade flows was considered and addressed if required
• Testing: New code requires new unit tests. New features and bug fixes require at least on e2e test
• Documentation: A user-guide update was considered and is present (link) or not required. You want a user-guide update if it's a user facing feature / API change.
• Community: Announcement to kubevirt-dev was considered

Release note:

NONE

[assafad]

Very nice, thanks @machadovilaca!
/lgtm

We need to make sure those changes are applied in openshift/runbooks before enabling the runbooks sync tool, and after this PR is merged, or else this tool will open dozens of PRs.