Mention https://textmate-grammars-themes.netlify.app/ in the docs

[zummenix]

Documentation issue

Summary

It seems to me that the https://textmate-grammars-themes.netlify.app is mentioned only in the change log

Proposed solution

Mention the https://textmate-grammars-themes.netlify.app in Syntax Highlighting and Configuration sections (somewhere inside the [markdown.highlighting]) of the docs

[zummenix]

Slightly related #3092