[doc]The DDL and DQL column names in the context do not match

[ZmmBigdata]

Purpose

Linked issue: close #xxx

What is the purpose of the change:
Fix the issue of mismatched DDL and DQL column names in the context, ensuring that the query statement is consistent with the table structure definition.

Brief change log

Please describe the changes:
https://alibaba.github.io/fluss-docs/docs/table-design/table-types/log-table/
The DDL and DQL column names in the context do not match:

1. Added a 'timestamp' column in the DDL definition to ensure that the table structure includes a timestamp field.
2. Modified the 'SELECT' statement to explicitly specify the column names for the query:
   -Original statement: SELECT * FROM log_table WHERE timestamp>'2023-01-01';
   -New statement: SELECT order_i, item_id FROM log_table WHERE timestamp>'2023-01-01';
3. Optimized the description of query columns, clearly stating that only the 'order_id', 'item_id', and 'timestamp' columns are accessed, and other columns (such as' address' and 'amount') will be automatically pruned by the database and will not participate in storage and reading.
   
   

API and Format

Does this change affect API or storage format:

• 是
• 否
  本次修改仅调整了 SQL 查询语句和表结构定义，不影响对外 API 或数据存储格式。

Documentation

Does this change introduce a new feature:

• 是
• 否
  本次修改是对现有功能的修复和优化，无需新增文档。

[wuchong]

I think the filter condition also doesn't work, because the '2023-01-01' is not a timestamp type. Could you also replace this with other meaningful condition?

[ZmmBigdata]

I think the filter condition also doesn't work, because the '2023-01-01' is not a timestamp type. Could you also replace this with other meaningful condition?

Wait a moment, look look

[ZmmBigdata]

The timestamp field name has been changed to dt