"SQL上线规范和要求 | Online Serving下LAST JOIN的使用规范" example is not correct

[zhanghaohit]

Bug Description
Now the doc looks like this:

Online Serving下LAST JOIN的使用规范

• Join type仅支持LAST JOIN类型
• 至少有一个JOIN条件是形如left_table.column=right_table.column的EQUAL条件，并且rgith_table.column列需要命中右表的索引
• 带排序LAST JOIN的情况下，ORDER BY只能支持列表达式，并且列需要命中右表索引的时间列

Example: 支持上线的简单SELECT查询语句范例

CREATE DATABASE db1;

USE db1;
CREATE TABLE t1 (col0 STRING, col1 int, std_time TIMESTAMP, INDEX(KEY=col1, TS=std_time, TTL_TYPE=absolute, TTL=30d));
-- SUCCEED: Create successfully

desc t1;
 --- ---------- ----------- ------ --------- 
  #   Field      Type        Null   Default  
 --- ---------- ----------- ------ --------- 
  1   col0       Varchar     YES             
  2   col1       Int         YES             
  3   std_time   Timestamp   YES             
 --- ---------- ----------- ------ --------- 
 --- -------------------- ------ ---------- ---------- --------------- 
  #   name                 keys   ts         ttl        ttl_type       
 --- -------------------- ------ ---------- ---------- --------------- 
  1   INDEX_0_1639524729   col1   std_time   43200min   kAbsoluteTime  
 --- -------------------- ------ ---------- ---------- --------------- 

Expected Behavior
The example should be for the LAST JOIN example. Not the create table example.

[aceforeverd]

OpenMLDB/docs/zh/reference/sql/deployment_manage/ONLINE_SERVING_REQUIREMENTS.md

Line 9 in 607f32b

## Online Serving Op List

[aceforeverd]

High-priority Bugs (0.5.x)

[aceforeverd]

fix by #2195