Add docs for configuring storage and isolation for cache policies

[desertaxle]

Adds documentation for changes introduced in #15382.

Checklist

• This pull request references any related issue by including "closes <link to issue>"
  • If no issue exists and your change is not a small fix, please create an issue first.
• If this pull request adds new functionality, it includes unit tests that cover the changes
• If this pull request removes docs files, it includes redirect settings in mint.json.
• If this pull request adds functions or classes, it includes helpful docstrings.

[codspeed-hq]

CodSpeed Performance Report

Merging #15397 will not alter performance

_{Comparing cache-enhancements-docs (eb09fec) with main (8e91cd5)}

Summary

✅ 3 untouched benchmarks