re-arrange exports, some doc string updates

src/ws/client.rs

@@ -268,6 +268,10 @@ struct Inner {
     closed: bool,
 }
 
+/// Future that implementes client websocket handshake process.
+///
+/// It resolves to a pair of `ClientReadr` and `ClientWriter` that
+/// can be used for reading and writing websocket frames.
 pub struct ClientHandshake {
     request: Option<SendRequest>,
     tx: Option<UnboundedSender<Bytes>>,