2.x: Update Error Handling Operators docs (#6266)
2.x: Update Error Handling Operators docs (#6266)

* Change document structure; update operator list

* Add examples

* Clarify which handler is invoked

* Use consistent wording in the descriptions

* Cleanup

NiteshKant/RxJava,ReactiveX/RxJava,reactivex/rxjava,artem-zinnatullin/RxJava,reactivex/rxjava,NiteshKant/RxJava,ReactiveX/RxJava,artem-zinnatullin/RxJava