Fixed start_link spec to include binary option on URL

Author: Matt Branton

src/websocket_client.erl

@@ -18,7 +18,7 @@
 -type opts() :: [opt()].
 
 %% @doc Start the websocket client
--spec start_link(URL :: string(), Handler :: module(), HandlerArgs :: list()) ->
+-spec start_link(URL :: string() | binary(), Handler :: module(), HandlerArgs :: list()) ->
                         {ok, pid()} | {error, term()}.
 start_link(URL, Handler, HandlerArgs) ->
     start_link(URL, Handler, HandlerArgs, []).