关于与 MySQL 可重复读隔离级别的区别的描述

[Jingyuma]

File: /transaction-isolation-levels.md

与 MySQL 可重复读隔离级别的区别
现在默认应该是使用悲观事务，会导致锁等待而不是事务回滚。
此处看起来需要修改。

[TomShawn]

/assign @cfzjywxk

[TomShawn]

@cfzjywxk PTAL how should we modify the doc. Thanks~

[cfzjywxk]

@TomShawn
The document needs to update.

[TomShawn]

@cfzjywxk is working on the transaction docs refactoring. By then, this issue can be addressed.

[cfzjywxk]

@you06
There are some inaccurate descriptions for the transaction and isolation overview document, PTAL if you have time.