Fix broken link in DM best practices

[alastori]

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)

Fixing broken link. It was [Use the relay log](#use-the relay-log). Changed to Use the relay log.

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

Tips for choosing the affected version(s):

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.

• master (the latest development version)
• v8.4 (TiDB 8.4 versions)
• v8.3 (TiDB 8.3 versions)
• v8.2 (TiDB 8.2 versions)
• v8.1 (TiDB 8.1 versions)
• v7.5 (TiDB 7.5 versions)
• v7.1 (TiDB 7.1 versions)
• v6.5 (TiDB 6.5 versions)
• v6.1 (TiDB 6.1 versions)
• v5.4 (TiDB 5.4 versions)
• v5.3 (TiDB 5.3 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

[alastori]

/label needs-cherry-pick-release-8.4
/label needs-cherry-pick-release-8.3
/label needs-cherry-pick-release-8.2
/label needs-cherry-pick-release-8.1
/label needs-cherry-pick-release-7.5
/label needs-cherry-pick-release-7.1
/label needs-cherry-pick-release-6.5

[ti-chi-bot]

@alastori: The label(s) needs-cherry-pick-release-8.4, needs-cherry-pick-release-8.2 cannot be applied. These labels are supported: 2024-tidb-docs-dash, contribution, first-time-contributor, for-future-release, good first issue, hacktoberfest-accepted, Hacktoberfest, help wanted, needs-cherry-pick-master, needs-cherry-pick-release-5.4, needs-cherry-pick-release-6.1, needs-cherry-pick-release-6.5, needs-cherry-pick-release-7.1, needs-cherry-pick-release-7.5, needs-cherry-pick-release-8.1, needs-cherry-pick-release-8.3, question, requires-followup, requires-version-specific-changes, special-week, website.

In response to this:

/label needs-cherry-pick-release-8.4
/label needs-cherry-pick-release-8.3
/label needs-cherry-pick-release-8.2
/label needs-cherry-pick-release-8.1
/label needs-cherry-pick-release-7.5
/label needs-cherry-pick-release-7.1
/label needs-cherry-pick-release-6.5

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.

[lilin90]

/lgtm

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-09-18 02:00:21.003140608 +0000 UTC m=+1012890.743564566: ☑️ agreed by lilin90.

[lilin90]

/approve

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: lilin90

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

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• OWNERS [lilin90]

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[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.5: #18919.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.1: #18920.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.5: #18921.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.1: #18922.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.2: #18923.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.3: #18924.