Incorrect error message in tone.py

[zmuranaka]

There is a typo in the error message when you try to play an invalid note. The error message (located in tone.py) says the following:

if match is None:
        raise InvalidNote(
            '%s is not a valid note. '
            'notes are A-F, are either normal, flat (b) or sharp (#) '
            'and of octave 0-8' % note
        )

but Pygame Zero can play all seven notes of A-G. It should say the following:

if match is None:
        raise InvalidNote(
            '%s is not a valid note. '
            'notes are A-G, are either normal, flat (b) or sharp (#) '
            'and of octave 0-8' % note
        )