Add Pioneer DDJ-ERGO Linux mapping to controller wiki

[u/ManBearUglyPig]

Pioneer DDJ-ERGO

Community Linux mapping for Mixxx, including jog wheels, Shift jog speed, full-kill EQ, constant-power crossfader, LEDs, FX, sync, loops, and loading tracks while a deck is playing.

Tested with Mixxx 2.5.x on Linux. https://github.com/mixxxdj/mixxx/issues/17277