update README

Author: nuclearace

README.md

@@ -91,6 +91,7 @@ Options
 - `forceWebsockets: Bool` Default is `false`. `true` forces the client to use WebSockets.
 - `nsp: String` Default is `"/"`
 - `cookies: [NSHTTPCookie]?` An array of NSHTTPCookies. Passed during the handshake. Default is nil.
+- `log: Bool` If `true` socket will log debug messages. Default is false.
 
 Methods
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