Fix size names in the SelectorGroup docs

packages/circuit-ui/components/SelectorGroup/SelectorGroup.mdx

@@ -30,9 +30,9 @@ Pass the `multiple` prop to allow users to select more than one option. Under th
 
 The `size` prop determines the padding of the options. There are three available sizes:
 
-- **mega**, the default size
-- **kilo**, used for compact layouts
-- **flexible**, used for more complex content within a selector which may define its own padding. Adds minimal equal padding on all sides.
+- **small**, used for compact layouts
+- **medium**, the default size
+- **flexible**, used for more complex content within a selector. Adds equal padding on all sides.
 
 <Story of={Stories.Sizes} />