[Docs] TOC of formatter configurations

[haras-unicorn]

There are some formatter configurations that need additional documentation so people are warned (in case of using prettier html formatter with various templating languages) or know which formatter to use (in case of rusftfmt it seems like it has multiple editions).

This would also create the need for PR and issue templates since contributors/issuers should be aware that they would need to update the TOC when adding new formatter configurations or updating old ones.