[docs] add tip on customizing look-controls
[docs] add tip on customizing look-controls

ngokevin/aframe,aframevr/aframe,mkungla/aframe,weddingdj/aframe,weddingdj/aframe,dmarcos/aframe,dmarcos/aframe,chenzlabs/aframe,wizgrav/aframe,ngokevin/aframe,wizgrav/aframe,RSpace/aframe,googlecreativelab/aframe,mkungla/aframe,aframevr/aframe,chenzlabs/aframe,RSpace/aframe,googlecreativelab/aframe