Add faq for namespace usage

Author: nuclearace

Usage Docs/FAQ.md

@@ -42,3 +42,13 @@ class SocketManager {
 }
 
 ```
+
+------
+
+Another case where this might happen is if you use namespaces in your socket.io application.
+
+In the JavaScript client a url that looks like `http://somesocketioserver.com/client` would be done with the `nsp` config.
+
+```swift
+let socket = SocketIOClient(socketURL: URL(string: "http://somesocketioserver.com/client")!, config: [.nsp("/client")])
+```