describe how to pass argument to error() method callback

README.md

@@ -158,9 +158,9 @@ Put the button in the normal state.
 Put the button in the success state. Call the callback or the onSuccess prop when going back to the normal state.
 Use `dontGoBackToNormal` flag to keep the button in success state (default is `false` so the button goes back to normal state after `durationSuccess`).
 
-##### error([callback, dontGoBackToNormal])
+##### error([callback, error, dontGoBackToNormal])
 
-Put the button in the error state. Call the callback or the onError prop when going back to the normal state.
+Put the button in the error state. Call the callback or the onError prop (with `error` argument) when going back to the normal state.
 Use `dontGoBackToNormal` flag to keep the button in error state (default is `false` so the button goes back to normal state after `durationError`).
 
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