[Cache] Clarify Cache Response Rule incompatibility with version management

[db-cloudflare]

Summary

Cache response rules do not work with version management. This PR updates the docs to clarify this.

Documentation checklist

• The change adheres to the documentation style guide.
• If a larger change - such as adding a new page- an issue has been opened in relation to any incorrect or out of date information that this PR fixes.
• Files which have changed name or location have been allocated redirects.