Add a description about how to resolve conflict of a cherry-pick PR

[JaySon-Huang]

Feature Request

• [ ] I have searched the issues of this repository and believe that this is not a duplicate.

Is your feature request related to a Issue or PR(Optional)

• Which project: All

• PR or Issue Link: https://github.com/pingcap/tidb/pull/25749

Describe the feature you'd like:

I want a description about how to resolve the conflict of a cherry-pick PR. More explicitly:

• If you have the write access to the cherry-pick branch
  • How to check the cherry-pick PR easily
  • After conflicts are resolved, how to push those commit to the original branch

A further issue maybe:

• If you don't have the write access to the cherry-pick branch, add a description about what you should do

Do you have any ideas on how to implement it?(Optional)

[ti-chi-bot]

Issues go stale after 90d of inactivity. Mark the issue as fresh with /remove-lifecycle stale. Stale issues rot after an additional 30d of inactivity and eventually close. If this issue is safe to close now please do so with /close. Send feedback to sig-community-infra or Mini256. /lifecycle stale

[ti-chi-bot]

Stale issues rot after 30d of inactivity. Mark the issue as fresh with /remove-lifecycle rotten. Rotten issues close after an additional 30d of inactivity. If this issue is safe to close now please do so with /close. Send feedback to sig-community-infra or Mini256. /lifecycle rotten