docs: fix incorrect description

null is not a valid IP address, so it will be 0.0.0.0.

Author: kenjis

user_guide_src/source/incoming/request.rst

@@ -19,8 +19,8 @@ Class Reference
 
     .. php:method:: getIPAddress()
 
-        :returns: The user's IP Address, if it can be detected, or null. If the IP address
-                    is not a valid IP address, then will return 0.0.0.0
+        :returns: The user's IP Address, if it can be detected. If the IP address
+                    is not a valid IP address, then will return 0.0.0.0.
         :rtype:   string
 
         Returns the IP address for the current user. If the IP address is not valid, the method