Fix the documentation of `Disposable` types.
Fix the documentation of `Disposable` types.

sandyway/ReactiveCocoa,walkingsmarts/ReactiveCocoa,ikesyo/ReactiveCocoa,ikesyo/ReactiveCocoa,sandyway/ReactiveCocoa,victorlin/ReactiveCocoa,victorlin/ReactiveCocoa,calebd/ReactiveCocoa,walkingsmarts/ReactiveCocoa,ohwutup/ReactiveCocoa,calebd/ReactiveCocoa,calebd/ReactiveCocoa,walkingsmarts/ReactiveCocoa,ReactiveCocoa/ReactiveSwift,ReactiveCocoa/ReactiveSwift,ohwutup/ReactiveCocoa,ReactiveCocoa/ReactiveSwift,ohwutup/ReactiveCocoa,victorlin/ReactiveCocoa,sandyway/ReactiveCocoa