Add search keywords for CheckButton and ButtonGroup

Author: Calinou

doc/classes/ButtonGroup.xml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8" ?>
-<class name="ButtonGroup" inherits="Resource" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../class.xsd">
+<class name="ButtonGroup" inherits="Resource" keywords="radio" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../class.xsd">
 	<brief_description>
 		A group of buttons that doesn't allow more than one button to be pressed at a time.
 	</brief_description>

doc/classes/CheckButton.xml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8" ?>
-<class name="CheckButton" inherits="Button" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../class.xsd">
+<class name="CheckButton" inherits="Button" keywords="switch, toggle" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../class.xsd">
 	<brief_description>
 		A button that represents a binary choice.
 	</brief_description>