add docs to Iterator to explicitly describe the Iterator protocol (#2385)
add docs to Iterator to explicitly describe the Iterator protocol (#2385)


kulibali/ponyc,kulibali/ponyc,Theodus/ponyc,dipinhora/ponyc,ponylang/ponyc,sgebbie/ponyc,kulibali/ponyc,ponylang/ponyc,jemc/ponyc,Theodus/ponyc,Praetonus/ponyc,sgebbie/ponyc,Theodus/ponyc,ponylang/ponyc,jemc/ponyc,cquinn/ponyc,cquinn/ponyc,Praetonus/ponyc,CausalityLtd/ponyc,Theodus/ponyc,Praetonus/ponyc,jemc/ponyc,dipinhora/ponyc,Theodus/ponyc,sgebbie/ponyc,kulibali/ponyc,Praetonus/ponyc,CausalityLtd/ponyc,cquinn/ponyc,sgebbie/ponyc,dipinhora/ponyc,cquinn/ponyc,sgebbie/ponyc,CausalityLtd/ponyc