Incorrect anchor in a link to the object cache documentation

[jdy68]

Hi,

In the “Site Health” tool, when the message “You should use a persistent object cache” appears, a link (Learn more about persistent object caching) takes you to the developer documentation.
The anchor for this link is incorrect (and therefore does not work).

Please, replace

​https://developer.wordpress.org/advanced-administration/performance/optimization/#persistent-object-cache

by

​https://developer.wordpress.org/advanced-administration/performance/optimization/#object-caching

Thanks

Related ticket: #58518

### Description
This PR addresses Trac Ticket #65477 by fixing a broken anchor link in the Site Health tool.

The "Learn more about persistent object caching" link previously directed users to https://developer.wordpress.org/advanced-administration/performance/optimization/#persistent-object-cache. This anchor is incorrect and does not work.

This update changes the anchor to the correct one: #object-caching.

### Testing Instructions

1. Navigate to Tools > Site Health in your WordPress admin dashboard.
2. If your local environment is not using a persistent object cache, you should see the recommended improvement: "You should use a persistent object cache".
3. Click the link "Learn more about persistent object caching."
4. Verify that the link correctly redirects to the specific #object-caching section on the Advanced Administration documentation page.

[sabernhardt]

​PR 186 edited the heading text more than three years ago, soon after r57793 updated the links to the Advanced Administration handbook. That makes #object-caching more established than #persistent-object-cache.

The #caching and #autoloaded-options anchors for the same handbook page work correctly (r58113 fixed the caching link and r58332 added the autoloaded options test).

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For future edits to heading text in the handbook, I would prefer to keep the existing anchor (with the ​markdown syntax) if it is still appropriate.