Fix format in TOC

[shichun-0415]

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)

Fix format in TOC

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

• master (the latest development version)
• v5.3 (TiDB DM 5.3 versions)
• v2.0 (TiDB DM 2.0 versions)
• v1.0 (TiDB DM 1.0 versions)

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

• This PR is translated from:
• 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:

• hfxsd
• lilin90

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.

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[CLAassistant]

All committers have signed the CLA.

[hfxsd]

LGTM

[lilin90]

LGTM

[hfxsd]

/merge

[ti-chi-bot]

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

Details

Commit hash: d0868c0

[ti-chi-bot]

In response to a cherrypick label: new pull request created: #852.

[ti-chi-bot]

In response to a cherrypick label: new pull request created: #853.