lack online help for queue number mode of zabbix.stats[,,,queue] and zabbix[stats,,,queue]

At ZBXNEXT-4907, zabbix[stats] internal item and zabbix.stats[] agent active items were added. Although they have queue mode, online helps are lacked.
So, I attached the patch.

In addition, send_internal_stats_json() is following.

948 if (SUCCEED == zbx_json_value_by_name(jp, ZBX_PROTO_TAG_TYPE, type, sizeof(type)) &&
949 0 == strcmp(type, ZBX_PROTO_VALUE_ZABBIX_STATS_QUEUE))
950 {
...
984 else
985

{ 986 zbx_json_addstring(&json, ZBX_PROTO_TAG_RESPONSE, ZBX_PROTO_VALUE_SUCCESS, ZBX_JSON_TYPE_STRING); 987 zbx_json_addobject(&json, ZBX_PROTO_TAG_DATA); 988 989 zbx_get_zabbix_stats(&json); 990 991 zbx_json_close(&json); 992 }

In l.948, type is not ZBX_PROTO_VALUE_ZABBIX_STATS_QUEUE, it executes for data mode. It should be "error"