Missing language IDs for Emmet supported languages

<!-- ⚠️⚠️ Do Not Delete This! bug_report_template ⚠️⚠️ --> <!-- Please read our Rules of Conduct: https://opensource.microsoft.com/codeofconduct/ --> <!-- Please search existing issues to avoid creating duplicates. --> <!-- Also please test using the latest insiders build to make sure your issue has not already been fixed: https://code.visualstudio.com/insiders/ --> In the docs, section [How to expand Emmet abbreviations](https://code.visualstudio.com/docs/editor/emmet#_how-to-expand-emmet-abbreviations-and-snippets), it lists the file types where Emmet is available. You can see it mentions the languages: stylus, slim and haml. Yet it seems they do not have Language IDs. If you wanted to disable Emmet support for these file types, you would need to create your own language IDs I guess?  If you are associating features with file types, would this not be a case for having these Language IDs included?