add some desc

[glkappe]

Most rds do not allow reload permission, so add necessary instructions

First-time contributors' checklist

• [ ] I've signed Contributor License Agreement that's required for repo owners to accept my contribution.

What is changed, added or deleted? (Required)

Which TiDB version(s) do your changes apply to? (Required)

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By default, CHOOSE MASTER ONLY so your changes will be applied to the next TiDB major or minor releases. If your PR involves a product feature behavior change or a compatibility change, CHOOSE THE AFFECTED RELEASE BRANCH(ES) AND MASTER.

For details, see tips for choosing the affected versions (in Chinese).

• [x] master (the latest development version)
• [x] v6.2 (TiDB 6.2 versions)
• [x] v6.1 (TiDB 6.1 versions)
• [x] v5.4 (TiDB 5.4 versions)
• [ ] v5.3 (TiDB 5.3 versions)
• [ ] v5.2 (TiDB 5.2 versions)
• [ ] v5.1 (TiDB 5.1 versions)
• [ ] v5.0 (TiDB 5.0 versions)

What is the related PR or file link(s)?

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• Other reference link(s):

Do your changes match any of the following descriptions?

• [ ] Delete files
• [ ] Change aliases
• [ ] Need modification after applied to another branch
• [ ] Might cause conflicts after applied to another branch

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• lance6716

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[shichun-0415]

/remove status LGT1 /status LGT2 /merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 560bda15210f5e3c5a771cef84a3ac0e11a800d5

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.5: #13412.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.6: #13413.