docs(count): remove reference to thisArg
docs(count): remove reference to thisArg

Remove reference to a thisArg argument given to count() operator in its JSDoc.

For issue #878.

jinroh/RxJS,IgorMinar/RxJS,RxJS-CN/RxJS-Docs-CN,martinsik/rxjs,jadbox/RxJS,adrianomelo/RxJSNext,elliotschi/rxjs,trxcllnt/RxJS,adrianomelo/RxJS-1,martinsik/rxjs,Brocco/RxJS,elliotschi/rxjs,jinroh/RxJS,jadbox/RxJS,elliotschi/rxjs,elliotschi/rxjs,jayphelps/rxjs,adrianomelo/RxJS-1,staltz/RxJSNext,adrianomelo/RxJS-1,gluck/RxJS,ReactiveX/RxJS,justinwoo/RxJS,figueredo/RxJS,ReactiveX/rxjs,gluck/RxJS,jadbox/RxJS,SangKa/RxJS-Docs-CN,SangKa/RxJS-Docs-CN,ReactiveX/RxJS,kwonoj/RxJS,Igorbek/rxjs5,kwonoj/RxJS,staltz/RxJSNext,gluck/RxJS,jayphelps/rxjs,justinwoo/RxJS,martinsik/rxjs,Igorbek/rxjs5,Brocco/RxJS,Igorbek/rxjs5,adrianomelo/RxJSNext,RxJS-CN/RxJS-Docs-CN,justinwoo/RxJS,jayphelps/rxjs,jinroh/RxJS,staltz/RxJSNext,IgorMinar/RxJS,benlesh/RxJS,adrianomelo/RxJS-1,saneyuki/RxJS,ReactiveX/rxjs,Igorbek/rxjs5,gluck/RxJS,kwonoj/RxJS,RxJS-CN/RxJS-Docs-CN,benlesh/RxJS,ReactiveX/RxJS,figueredo/RxJS,ReactiveX/rxjs,justinwoo/RxJS,saneyuki/RxJS,figueredo/RxJS,RxJS-CN/RxJS-Docs-CN,benlesh/RxJS,SangKa/RxJS-Docs-CN,robwormald/RxJS,SangKa/RxJS-Docs-CN,robwormald/RxJS,adrianomelo/RxJSNext,trxcllnt/RxJS,jinroh/RxJS,robwormald/RxJS,figueredo/RxJS,ReactiveX/RxJS,martinsik/rxjs,staltz/RxJSNext,jadbox/RxJS,Brocco/RxJS,adrianomelo/RxJSNext,kwonoj/RxJS,benlesh/RxJS,jayphelps/rxjs,jayphelps/rxjs,Brocco/RxJS,ReactiveX/rxjs,trxcllnt/RxJS,trxcllnt/RxJS,robwormald/RxJS