add curation/evangelizing to contribution guide
add curation/evangelizing to contribution guide

RSpace/aframe,weddingdj/aframe,wizgrav/aframe,fernandojsg/aframe,darkwing/aframe,chenzlabs/aframe,dmarcos/aframe,weddingdj/aframe,ngokevin/aframe,fernandojsg/aframe,aframevr/aframe,jaxmolina/ar,googlecreativelab/aframe,darkwing/aframe,aframevr/aframe,googlecreativelab/aframe,chenzlabs/aframe,RSpace/aframe,mkungla/aframe,ngokevin/aframe,dmarcos/aframe,jaxmolina/ar,wizgrav/aframe,mkungla/aframe