[Documentation] Improve ASCollectionNode docs. (#2318)
[Documentation] Improve ASCollectionNode docs. (#2318)

* Improve ASCollectionNode docs.

* Spelling fix, thanks @hannahmbanana

* Address Adlai's comments

samhsiung/AsyncDisplayKit,rmls/AsyncDisplayKit,tomizimobile/AsyncDisplayKit,bimawa/AsyncDisplayKit,facebook/AsyncDisplayKit,lappp9/AsyncDisplayKit,aaronschubert0/AsyncDisplayKit,JetZou/AsyncDisplayKit,JetZou/AsyncDisplayKit,harryworld/AsyncDisplayKit,rahul-malik/AsyncDisplayKit,samhsiung/AsyncDisplayKit,smyrgl/AsyncDisplayKit,flovouin/AsyncDisplayKit,rahul-malik/AsyncDisplayKit,harryworld/AsyncDisplayKit,aaronschubert0/AsyncDisplayKit,aaronschubert0/AsyncDisplayKit,george-gw/AsyncDisplayKit,chrisdanford/AsyncDisplayKit,flovouin/AsyncDisplayKit,tomizimobile/AsyncDisplayKit,bimawa/AsyncDisplayKit,gazreese/AsyncDisplayKit,rahul-malik/AsyncDisplayKit,george-gw/AsyncDisplayKit,bimawa/AsyncDisplayKit,george-gw/AsyncDisplayKit,aaronschubert0/AsyncDisplayKit,facebook/AsyncDisplayKit,romyilano/AsyncDisplayKit,chrisdanford/AsyncDisplayKit,gazreese/AsyncDisplayKit,george-gw/AsyncDisplayKit,romyilano/AsyncDisplayKit,rahul-malik/AsyncDisplayKit,rmls/AsyncDisplayKit,rmls/AsyncDisplayKit,JetZou/AsyncDisplayKit,samhsiung/AsyncDisplayKit,flovouin/AsyncDisplayKit,maicki/AsyncDisplayKit,lappp9/AsyncDisplayKit,flovouin/AsyncDisplayKit,rmls/AsyncDisplayKit,maicki/AsyncDisplayKit,flovouin/AsyncDisplayKit,maicki/AsyncDisplayKit,samhsiung/AsyncDisplayKit,romyilano/AsyncDisplayKit,harryworld/AsyncDisplayKit,harryworld/AsyncDisplayKit,facebook/AsyncDisplayKit,maicki/AsyncDisplayKit,tomizimobile/AsyncDisplayKit,chrisdanford/AsyncDisplayKit,bimawa/AsyncDisplayKit,JetZou/AsyncDisplayKit,chrisdanford/AsyncDisplayKit,smyrgl/AsyncDisplayKit,smyrgl/AsyncDisplayKit,JetZou/AsyncDisplayKit,tomizimobile/AsyncDisplayKit,smyrgl/AsyncDisplayKit,gazreese/AsyncDisplayKit,maicki/AsyncDisplayKit,romyilano/AsyncDisplayKit,facebook/AsyncDisplayKit,harryworld/AsyncDisplayKit,tomizimobile/AsyncDisplayKit,aaronschubert0/AsyncDisplayKit,gazreese/AsyncDisplayKit,lappp9/AsyncDisplayKit,rmls/AsyncDisplayKit,lappp9/AsyncDisplayKit