Picker docs update.
Picker docs update.

--HG--
branch : feature/sortable-meshes

shinate/engine,3DGEOM/engine,aidinabedi/playcanvas-engine,horryq/engine-1,maxwellalive/engine,playcanvas/engine,aidinabedi/playcanvas-engine,SuperStarPL/engine,sanyaade-teachings/engine,SuperStarPL/engine,nizihabi/engine,nizihabi/engine,horryq/engine-1,RainsSoft/engine,playcanvas/engine,sereepap2029/playcanvas,maxwellalive/engine,RainsSoft/engine,shinate/engine,horryq/engine-1,H1Gdev/engine,sereepap2029/playcanvas,maxwellalive/engine,MicroWorldwide/PlayCanvas,nizihabi/engine,H1Gdev/engine,sanyaade-teachings/engine,sereepap2029/playcanvas,3DGEOM/engine,guycalledfrank/engine,3DGEOM/engine,SuperStarPL/engine,MicroWorldwide/PlayCanvas,sanyaade-teachings/engine,shinate/engine,guycalledfrank/engine,RainsSoft/engine