Slight innacuracy in `ip_address` `try_value_to` example

[pdimov]

    boost::system::result< unsigned char > oct1
        = try_value_to< unsigned char >( arr[0] );
    if( !oct1 )
        return make_error_code( std::errc::invalid_argument );

This should be

    if( !oct1 )
        return oct1.error();

so as to not discard the error returned from the nested try_value_to (which is going to be more informative and may include a source location).