basic features: fix anchor link

[Oreoxmt]

What is changed, added or deleted? (Required)

Update the link for invisible indexes to point correctly from /sql-statements/sql-statement-add-index.md to /sql-statements/sql-statement-create-index.md#invisible-index.

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• Delete files
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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-04-02 06:21:51.845105303 +0000 UTC m=+338573.372645847: ☑️ agreed by hfxsd.

[Oreoxmt]

/approve

[ti-chi-bot]

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[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.6: #16975.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.0: #16976.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.1: #16977.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.4: #16978.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.5: #16979.