Update documentation examples.

docs/common-patterns.rst

@@ -198,7 +198,7 @@ restrictions highly readable.
             );
             _;
             if (msg.value > _amount)
-                msg.sender.send(msg.value - _amount);
+                msg.sender.transfer(msg.value - _amount);
         }
 
         function forceOwnerChange(address _newOwner)