`user_role` callback signature appears to be wrong in documentation

[mrenvoize]

The documentation states the callback signature of the user_role routine is:

sub {
    my ($app,$extradata) = @_;
    ...
    return $role;
}

But the code appears to call it as

sub {
    my ($app,$user,$extradata) = @_;
    ...
    return $role;
}

[byterock]

Ok this is fixed in the code fortunetly it had not impact