Updated release notes for Subject[T]
Updated release notes for Subject[T]

joohnnie/RxScala,zhongdj/RxScala,hermanbanken/RxScala,samuelgruetter/RxScala,samuelgruetter/RxScala,jbripley/RxScala,jbripley/RxScala,ReactiveX/RxScala,zjrstar/RxScala,hermanbanken/RxScala,TracyLu/RxScala