Suggest removing "Projects that use osu!framework" section of readme

[Joehuu]

There's already an integrated "Used by" section on the right side:

You can't really sort the repos yet, so another option is just listing notable ones. The currently listed repos (excluding osu!) are not maintained and one even changed frameworks.

[peppy]

Hmm, I'd still likely to list larger projects which use osu!framework to highlight them as use cases.