docs: add Lock tables in Set Locking

[youngkiu]

Description of change

I had a similar issue #4084.

So, I searched the documentation, and although there was a Lock version, there was no explanation for the Lock tables argument, so I added it.

https://orkhan.gitbook.io/typeorm/docs/select-query-builder#set-locking

---

The issue situation I encountered is as follows.

        transaction
            .getRepository(User)
            .createQueryBuilder('user')
            .setLock('pessimistic_write')
            .leftJoinAndSelect('user.post', 'post')
            .where('user.id = :userId', { userId })
            .getOne();

PlatformTools.ts:239error: error: FOR UPDATE cannot be applied to the nullable side of an outer join

I solved it by looking at the typeorm internal code and modifying it as follows.

        transaction
            .getRepository(User)
            .createQueryBuilder('user')
-            .setLock('pessimistic_write')
+            .setLock('pessimistic_write', undefined, ['user'])
            .leftJoinAndSelect('user.post', 'post')
            .where('user.id = :userId', { userId })
            .getOne();

Pull-Request Checklist

• Code is up-to-date with the master branch
• npm run format to apply prettier formatting
• npm run test passes with this change
• This pull request links relevant issues as Fixes #0000
• There are new or updated unit tests validating the change
• Documentation has been updated to reflect this change
• The new commits follow conventions explained in CONTRIBUTING.md