Add a notice about ingress annotations that affect cluster level options (#2992)

* Add a notice about cluster level ingress annotations.

* Convert into NOTE block and use anchors for linking.

* Move the annotation to the first column.

* Use a heading since cannot use inline HTML.

Author: specialforest

samples/KubernetesIngress.Sample/README.md

@@ -93,18 +93,23 @@ The table below lists the available annotations.
 |yarp.ingress.kubernetes.io/output-cache-policy|string|
 |yarp.ingress.kubernetes.io/backend-protocol|string|
 |yarp.ingress.kubernetes.io/cors-policy|string|
-|yarp.ingress.kubernetes.io/health-check|[ActivateHealthCheckConfig](https://learn.microsoft.com/dotnet/api/yarp.reverseproxy.configuration.activehealthcheckconfig)|
-|yarp.ingress.kubernetes.io/http-client|[HttpClientConfig](https://learn.microsoft.com/dotnet/api/yarp.reverseproxy.configuration.httpclientconfig)|
-|yarp.ingress.kubernetes.io/http-request|[ForwarderRequestConfig](https://learn.microsoft.com/en-us/dotnet/api/yarp.reverseproxy.forwarder.forwarderrequestconfig)|
-|yarp.ingress.kubernetes.io/load-balancing|string|
+|yarp.ingress.kubernetes.io/health-check [\*](#cluster-level-annotations)|[ActivateHealthCheckConfig](https://learn.microsoft.com/dotnet/api/yarp.reverseproxy.configuration.activehealthcheckconfig)|
+|yarp.ingress.kubernetes.io/http-client [\*](#cluster-level-annotations)|[HttpClientConfig](https://learn.microsoft.com/dotnet/api/yarp.reverseproxy.configuration.httpclientconfig)|
+|yarp.ingress.kubernetes.io/http-request [\*](#cluster-level-annotations)|[ForwarderRequestConfig](https://learn.microsoft.com/en-us/dotnet/api/yarp.reverseproxy.forwarder.forwarderrequestconfig)|
+|yarp.ingress.kubernetes.io/load-balancing [\*](#cluster-level-annotations)|string|
 |yarp.ingress.kubernetes.io/route-metadata|Dictionary<string, string>|
-|yarp.ingress.kubernetes.io/session-affinity|[SessionAffinityConfig](https://learn.microsoft.com/dotnet/api/yarp.reverseproxy.configuration.sessionaffinityconfig)|
+|yarp.ingress.kubernetes.io/session-affinity [\*](#cluster-level-annotations)|[SessionAffinityConfig](https://learn.microsoft.com/dotnet/api/yarp.reverseproxy.configuration.sessionaffinityconfig)|
 |yarp.ingress.kubernetes.io/transforms|List<Dictionary<string, string>>|
 |yarp.ingress.kubernetes.io/route-headers|List<[RouteHeader](https://learn.microsoft.com/dotnet/api/yarp.reverseproxy.configuration.routeheader)>|
 |yarp.ingress.kubernetes.io/route-queryparameters|List<[RouteQueryParameter](https://learn.microsoft.com/dotnet/api/yarp.reverseproxy.configuration.routequeryparameter)>|
 |yarp.ingress.kubernetes.io/route-order|int|
 |yarp.ingress.kubernetes.io/route-methods|List<string>|
 
+#### Cluster-level annotations
+
+> [!NOTE]
+> Annotations marked with **\*** configure the YARP cluster, not the route. A cluster is identified by backend service name, namespace, and port. Multiple ingress rules targeting the same backend share the cluster, so conflicting values result in non-deterministic behavior. Ensure consistent values across all ingress rules for the same backend.
+
 #### Authorization Policy
 
 See https://learn.microsoft.com/aspnet/core/fundamentals/servers/yarp/authn-authz for a list of available policies, or how to add your own custom policies.