Extra Tip: Radio Buttons example is wrong/obsolete

[g0dd4rd]

The "Extra Tip: Radio Buttons" contains code that throws error because the self.radio_toggle call is invalid.

[Taiko2k]

I indented it to be implied that you need to create that function yourself. I'm actually considering removing the example python files since its becoming difficult to maintain, or at least split them up more, but I haven't got there yet. For now ill just add an explicit mention that you need to create that function.