Fix custom middleware limitations (#18178)

* Fix #18177

* Document also 3.0, fix typo

* Update middleware.md

* Update middleware.md

* Update middleware.md

* Update middleware.md

* #18177: update middleware.md

Co-authored-by: Rick Anderson <3605364+Rick-Anderson@users.noreply.github.com>

Author: yringler

aspnetcore/performance/caching/middleware.md

@@ -38,6 +38,8 @@ The sample app adds headers to control caching on subsequent requests:
 
 [!code-csharp[](middleware/samples_snippets/3.x/AddHeaders.cs)]
 
+<!-- make same change here once approved -->
+
 Response Caching Middleware only caches server responses that result in a 200 (OK) status code. Any other responses, including [error pages](xref:fundamentals/error-handling), are ignored by the middleware.
 
 > [!WARNING]
@@ -178,6 +180,10 @@ The sample app adds headers to control caching on subsequent requests:
 
 [!code-csharp[](middleware/samples_snippets/2.x/AddHeaders.cs)]
 
+The preceding headers are not written to the response and are overriden when a controller, action, or Razor Page:
+
+* Has a [[ResponseCache]](xref:Microsoft.AspNetCore.Mvc.ResponseCacheAttribute) attribute. This applies even if a property isn't set. For example, omitting the [VaryByHeader] property (/aspnet/core/performance/caching/response#vary) will cause the corresponding header to be removed from the response.
+
 Response Caching Middleware only caches server responses that result in a 200 (OK) status code. Any other responses, including [error pages](xref:fundamentals/error-handling), are ignored by the middleware.
 
 > [!WARNING]