Add SoundSystem to the Tool section

[Bob]

I've released SoundSystem, which is a modernized audio driver for GameBoy Tracker (aka the Paragon 5 music player).

Can this be added to the Tools section?

Thanks!

[Antonio Vivace]

LGTM. Any opinion on this, @gbdev/awesome-gb?

[Duo]

I think this is fantastic, plus it adds a great example of clean code and documentation.