Update textinput.md (facebook#4131)

remove useEffect/componentDidMount

Author: usrbowe

docs/textinput.md

@@ -231,7 +231,7 @@ If `false`, disables auto-correct. The default value is `true`.
 
 ### `autoFocus`
 
-If `true`, focuses the input on `componentDidMount` or `useEffect`. The default value is `false`.
+If `true`, focuses the input. The default value is `false`.
 
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