Change docs link for cert manager (#2914)

[ti-chi-bot]

This is an automated cherry-pick of #2914

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• I've signed the Contributor License Agreement, which is required for the repository owners to accept my contribution.

What is changed, added, or deleted? (Required)

The docs link points to the v0.11 docs which now link to the release notes, which isn't what we want.

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

• master (the latest development version for v1.x)
• feature/v2 (the latest development version for v2.x)
• v2.0 (TiDB Operator 2.0 versions)
• v1.6 (TiDB Operator 1.6 versions)
• v1.5 (TiDB Operator 1.5 versions)
• v1.4 (TiDB Operator 1.4 versions)
• v1.3 (TiDB Operator 1.3 versions)

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

• This PR is translated from:
• Other reference link(s):

[Oreoxmt]

/approve

[ti-chi-bot]

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