docs: Add GitHub action to run checks on Markdown content during pull-request

[bryantbiggs]

What does this PR do?

• Add GitHub action to run checks on Markdown content during pull-request
  • You can see it in action here https://github.com/bryantbiggs/boop/pull/1 (after merge I can follow up with a PR to resolve the linting issues its caught)

Motivation

• Keep things in check to avoid changes with lots of whitespace noise due to formatting (docs: Update and standardize examples to follow conventions defined in pre-commit checks #424)

More

• Yes, I have tested the PR using my local account setup (Provide any test evidence report under Additional Notes)
• Yes, I have added a new example under examples to support my PR
• Yes, I have created another PR for add-ons under add-ons repo (if applicable)
• Yes, I have updated the docs for this feature
• Yes, I ran pre-commit run -a with this PR

Note: Not all the PRs required examples and docs except a new pattern or add-on added.

For Moderators

• E2E Test successfully complete before merge?

Additional Notes

[bryantbiggs]

just saw we have super-lint so closing until I see what we already have in place that might cover