✨ FEAT - Add frontmatter block check to Markdown validator GitHub Action

[JackDevAU]

CC: @bradystroud @adamcogan @BrookJeynes

Hi Team,

Issue

As seen in a recent content change: SSWConsulting/SSW.Rules.Content#7142
Having multiple --- frontmatter blocks inside a rule breaks Rules. This is also quite a hard issue to spot.

Tasks

• Add multiple frontmatter check into the Content Validation GitHub Action

[JackDevAU]

There is no real way to check this as --- can be used a separator. For a similar but different approach - I have experimented with a markdown formatter and validator. Which runs as a GitHub Action.

• Get checked by: @bradystroud or @adamcogan

[JackDevAU]

This has now been added to the Content repo and is running as validate-markdown.