docs: Remove feature support page (#316)

With the 0.6.0 release we'll check the last box, and we have feature
parity with Java according to this table. I would prefer creating
tickets on Github to point out the gaps rather than this page.

Author: Fokko

mkdocs/docs/SUMMARY.md

@@ -22,7 +22,6 @@
 - [CLI](cli.md)
 - [API](api.md)
 - [Contributing](contributing.md)
-- [Feature support](feature-support.md)
 - Releases
     - [Verify a release](verify-release.md)
     - [How to release](how-to-release.md)