Update dashboard FAQ

[shhdgit]

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)

Added a new FAQ for TiDB Dashboard

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

• master (the latest development version)
• v5.0 (TiDB 5.0 versions)
• v4.0 (TiDB 4.0 versions)
• v3.1 (TiDB 3.1 versions)
• v3.0 (TiDB 3.0 versions)
• v2.1 (TiDB 2.1 versions)

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

• Other reference link(s): tidb-dashboard#902

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

[TomShawn]

/label needs-cherry-pick-5.0
/label needs-cherry-pick-master
/translation done
/cc @breeswish
/assign @shhdgit

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• breeswish

To complete the pull request process, please ask the reviewers in the list to review by filling /cc @reviewer in the comment.
After your PR has acquired the required number of LGTMs, you can assign this pull request to the committer in the list by filling /assign @committer in the comment to help you merge this pull request.

The full list of commands accepted by this bot can be found here.

Details

Reviewer can indicate their review by writing /lgtm in a comment.
Reviewer can cancel approval by writing /lgtm cancel in a comment.

[TomShawn]

/label requires-version-specific-changes
/hold

[TomShawn]

/hold

[shhdgit]

Updated, PTAL.

[TomShawn]

@shhdgit Please help confirm whether this PR content applies to v5.1. Thanks~

[shhdgit]

Yes, v5.1 can also be applied.

[breezewish]

@TomShawn PTAL, thanks!

[qiancai]

This PR is closed because the author created a new PR (#6559) in master to cover the same changes.