Document Handle::default() behavior (#359)

tokio-tcp/src/listener.rs

@@ -159,6 +159,7 @@ impl TcpListener {
     ///
     /// Finally, the `handle` argument is the event loop that this listener will
     /// be bound to.
+    /// Use `Handle::default()` to lazily bind to an event loop, just like `bind` does.
     ///
     /// The platform specific behavior of this function looks like:
     ///

tokio-tcp/src/stream.rs

@@ -69,8 +69,7 @@ impl TcpStream {
     ///
     /// This function will convert a TCP stream created by the standard library
     /// to a TCP stream ready to be used with the provided event loop handle.
-    /// The stream returned is associated with the event loop and ready to
-    /// perform I/O.
+    /// Use `Handle::default()` to lazily bind to an event loop, just like `connect` does.
     pub fn from_std(stream: net::TcpStream, handle: &Handle)
         -> io::Result<TcpStream>
     {