improve api documentation
improve api documentation

thanegill/RxSwift,petester42/RxSwift,kousun12/RxSwift,kousun12/RxSwift,kzaher/RxSwift,shiratsu/RxSwift,ashfurrow/RxSwift,hsoi/RxSwift,kzaher/RxSwift,tottakai/RxSwift,cfraz89/RxSwift,shiratsu/RxSwift,shiratsu/RxSwift,thanegill/RxSwift,kousun12/RxSwift,kzaher/RxSwift,cfraz89/RxSwift,KyoheiG3/RxSwift,thanegill/RxSwift,cfraz89/RxSwift,petester42/RxSwift,tottakai/RxSwift,KyoheiG3/RxSwift,kousun12/RxSwift,KyoheiG3/RxSwift,ReactiveX/RxSwift,ashfurrow/RxSwift,ashfurrow/RxSwift,hsoi/RxSwift,tottakai/RxSwift,thanegill/RxSwift,ashfurrow/RxSwift,ReactiveX/RxSwift,hsoi/RxSwift,kzaher/RxSwift,cfraz89/RxSwift,hsoi/RxSwift,petester42/RxSwift,ReactiveX/RxSwift,petester42/RxSwift