Clarify OutputCache intent and limitations for classic ASP.Net.

[StephenMolloy]

This pull request improves the documentation for output caching in .NET Framework applications by clarifying how cache variation settings like VaryByParam and VaryByHeader work, and by adding important guidance about not relying on cache variation for isolating sensitive content. The updates emphasize that output caching is a performance optimization and that isolation for personalized or sensitive responses must be enforced separately.

Clarification and guidance on output caching:

• docs/framework/performance/caching-in-net-framework-applications.md: Expanded the explanation of output caching, detailing how VaryBy settings (such as VaryByParam, VaryByHeader, VaryByCustom, and VaryByContentEncoding) determine which representations are cached, and added a warning not to use cache variation for isolating sensitive or personalized content.
• docs/framework/wcf/feature-details/caching-support-for-wcf-web-http-services.md: Added a warning that the varyByParam setting should not be used to isolate sensitive or personalized responses, and that required isolation should be enforced independently of cache configuration.
• docs/framework/wcf/samples/aspnet-caching-integration.md: Added a similar warning regarding the use of varyByParam and varyByHeader in output caching, emphasizing that they are for performance optimization and not for isolating classes of content.## Summary

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Internal previews

📄 File	🔗 Preview link
docs/framework/performance/caching-in-net-framework-applications.md	docs/framework/performance/caching-in-net-framework-applications
docs/framework/wcf/feature-details/caching-support-for-wcf-web-http-services.md	docs/framework/wcf/feature-details/caching-support-for-wcf-web-http-services
docs/framework/wcf/samples/aspnet-caching-integration.md	docs/framework/wcf/samples/aspnet-caching-integration

[Copilot]

Pull request overview

This pull request clarifies how ASP.NET output caching variation works in .NET Framework scenarios, and adds consistent guidance that cache variation is for performance—not for isolating sensitive or personalized responses.

Changes:

• Expanded output caching explanation, including how VaryBy* settings influence cached representations.
• Added consistent IMPORTANT warnings across relevant docs that cache variation doesn’t enforce security or isolation boundaries.
• Updated the WCF + ASP.NET output caching integration sample documentation to include the same guidance.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
docs/framework/wcf/samples/aspnet-caching-integration.md	Adds an IMPORTANT warning about not using cache variation to isolate sensitive or personalized content.
docs/framework/wcf/feature-details/caching-support-for-wcf-web-http-services.md	Adds the same IMPORTANT warning; also contains a minor attribute-name inconsistency called out in review comments.
docs/framework/performance/caching-in-net-framework-applications.md	Expands the “Output Caching” section with explanation of alternate representations and adds an IMPORTANT warning about isolation limitations.