Delete some copy/paste docs (#444)
Delete some copy/paste docs (#444)

These docs are copied from the `Client` class. When a method is an
`@override` and has no doc, dartdoc will already duplicate the docs from
the overridden method - there is no need to copy the docs manually.
dart-lang/http,dart-lang/http,dart-lang/http,dart-lang/http,dart-lang/http,dart-lang/http,dart-lang/http,dart-lang/http