No issue to link – this was a problem we discovered while updating the
Registry website
## Description
This PR adds (very) basic validation for the GitHub Flavored Markdown
alerts that we allow contributors to add to their README files. The
errors that get generated should be correct, but the error messages
themselves aren't as helpful as they could be. I'm going to be handling
that in a separate PR, just so we can get this one in sooner.
### Changes made
- Added function for validating the core structure of all GFM alerts
- Updated existing README files that were failing the new validation
requirements
## Type of Change
- [ ] New module
- [x] Bug fix
- [ ] Feature/enhancement
- [ ] Documentation
- [ ] Other
e94dfd2df6