Add Nheko to featured clients.

[XVilka]

It's a shame that Cinny, which doesn't support a lot of stuff is listed in "featured" while much more advanced and feature-complete Nheko is somewhere below. Moreover, Nheko is Qt/C++ based client, which makes it faster as a native application and more suitable for older hardware (and there are lot of people with less beefy hardware out there). Since Nheko just recently made a release, I propose moving it to a "Featured" section.

https://github.com/Nheko-Reborn/nheko/releases/tag/v0.12.0

For example, Cinny doesn't support VoIP, Threads, and multi-language, while Nheko does.

I find it's funny that not a single native client is marked as "featured" now, almost like if Matrix pushes everyone to use Web-based software only.