Fix broken internal anchors reported for the performance docs page

[lbliii]

Context

While validating a docs-only install-snippet fix with make docs, Bengal completed the build but reported broken internal links on content/docs/about/performance.md.

Evidence

make docs exited 0, but the health check reported:

• content/docs/about/performance.md: #disable-auto-reload-in-production
• content/docs/about/performance.md: #pre-warm-template-cache
• content/docs/about/performance.md: #use-bytecode-cache
• plus additional broken anchors on the same page

A repository search did not find those anchor strings in current source docs, so this may be generated navigation/TOC metadata, stale cached site metadata, or an outdated hidden link source.

Proposed Scope

• Reproduce from a clean docs build/cache if needed.
• Identify whether the broken anchors come from generated performance-page navigation, cached metadata, or source content.
• Fix or remove stale anchor references without changing benchmark claims.

Done When

• make docs no longer reports broken links for content/docs/about/performance.md.
• Any cache/generated metadata explanation is documented if no source edit is required.