docs: add hyperlink to swizzling in Search page

[dandv]

Pre-flight checklist

• I have read the Contributing Guidelines on pull requests.
• If this is a code change: I have written unit tests and/or added dogfooding pages to fully verify the new behavior.
• If this is a new API or substantial change: the PR has an accompanying issue (closes #0000) and the maintainers have approved on my working plan.

Motivation

Those looking to evaluate Docusaurus's search capabilities, won't be familiar with swizzling.

[slorber]

Thanks

PR did not pass because links should rather use relative md file paths instead of relative paths: that makes them not sensitive to the presence of a trailingSlash

[netlify]

✅ [V2]

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[github-actions]

⚡️ Lighthouse report for the deploy preview of this PR

URL	Performance	Accessibility	Best Practices	SEO	PWA	Report
/	🟠 57	🟢 97	🟢 100	🟢 100	🟢 90	Report
/docs/installation	🟠 77	🟢 100	🟢 100	🟢 100	🟢 90	Report