Add GitHub workflow/action

[eveiscoull]

There should be a way to automate documentation linting as a GitHub workflow/action, available in the marketplace.

[eveiscoull]

Workflow should:

1. Require a pull request to review and post outputs on
   • Additionally, could require pull request to be labelled specifically to prevent spam
2. Require a ruleset to be specified (EN, specific rules)
3. Search the pull request for Markdown (.md) and text (.txt) files
4. Review the md/txt files for compliance to ruleset
5. Output results to pull request comments