Remove unnecessary issue templates

[modir]

Is there an existing issue for this?

• I have searched the existing issues

Offending URL

https://github.com/MithrilJS/docs/

Issue description

There is no need for all these issue templates in the docs repo:

[dead-claudia]

Removed the feature request link in 861d466 since I don't expect significant feature requests to be all that common here, but the rest is there on purpose. Most docs questions in my experience fall into one of three categories:

1. People missing small specifics that are already documented
2. People not entirely sure what they're asking
3. A mixture of 1 and 2

The formats of the discussion board and Zulip are better suited for these. While it's possible to work through them as issues, it's not very efficient. Zulip offers a place for live discussion (which GH Issues can't really accommodate), and the discussion board's threads feature helps isolate tangents from the main discussion better.