Add note about manager not being thread safe

Author: nuclearace

Source/SocketIO/Manager/SocketManager.swift

@@ -43,6 +43,8 @@ import Foundation
 /// To disconnect a socket and remove it from the manager, either call `SocketIOClient.disconnect()` on the socket,
 /// or call one of the `disconnectSocket` methods on this class.
 ///
+/// **NOTE**: The manager is not thread/queue safe, all interaction with the manager should be done on the `handleQueue`
+///
 open class SocketManager : NSObject, SocketManagerSpec, SocketParsable, SocketDataBufferable, ConfigSettable {
     private static let logType = "SocketManager"