Add markdown highlighting for @docs @moduledocs and @typedocs

[Terbium-135]

All credits for this fix going to https://github.com/SteffenDE

Fixes #87

[Blond11516]

@Terbium-135 Thanks for your work getting this resolved!

I've checked out the branch and it indeed seems to be working correctly.

I'll only need two things before I can approve and merge the branch:

1. Fixing the formatting (you can do so with npm run format)

2. Adding an entry at the top of CHANGELOG.md. It should look something like this:

   ## [Unreleased]
   
   ### Added
   
   - Added syntax highlighting...

   Be sure to thank Steffen and yourself in there!

[Terbium-135]

Added requested changes.
And Merry Christmas/Happy Holidays

[Blond11516]

Thanks! I updated the changelog, you deserve some credit too!

I'll merge this and give it a little bit before cutting a release, just in case.

Happy holidays to you too!