Differential Control docs and examples

[ArchdukeTim]

Please add more documentation and examples for differential control

[bhall-ctre]

Differential mechanisms have been reworked and expanded in 2026. Documentation is available at https://v6.docs.ctr-electronics.com/en/latest/docs/api-reference/mechanisms/differential/differential-overview.html (and subsequent pages), and we should have an example up by kickoff.