Returns a list of `DBParameterGroup` descriptions.
    CLI example to description of parameter group::

        salt myminion boto_rds.describe_parameter_group parametergroupname\
            region=us-east-1

def describe_parameter_group(name, Filters=None, MaxRecords=None, Marker=None,
                             region=None, key=None, keyid=None, profile=None):
    '''
    Returns a list of `DBParameterGroup` descriptions.
    CLI example to description of parameter group::

        salt myminion boto_rds.describe_parameter_group parametergroupname\
            region=us-east-1
    '''
    res = __salt__['boto_rds.parameter_group_exists'](name, tags=None,
                                                      region=region, key=key,
                                                      keyid=keyid,
                                                      profile=profile)
    if not res.get('exists'):
        return {'exists': bool(res)}

    try:
        conn = _get_conn(region=region, key=key, keyid=keyid, profile=profile)
        if not conn:
            return {'results': bool(conn)}

        kwargs = {}
        for key in ('Marker', 'Filters'):
            if locals()[key] is not None:
                kwargs[key] = str(locals()[key])  # future lint: disable=blacklisted-function

        if locals()['MaxRecords'] is not None:
            kwargs['MaxRecords'] = int(locals()['MaxRecords'])

        info = conn.describe_db_parameter_groups(DBParameterGroupName=name,
                                                 **kwargs)

        if not info:
            return {'results': bool(info), 'message':
                    'Failed to get RDS description for group {0}.'.format(name)}

        return {'results': bool(info), 'message':
                'Got RDS descrition for group {0}.'.format(name)}
    except ClientError as e:
        return {'error': __utils__['boto3.get_error'](e)}