Clarify Higress as third-party integration

Add clear designation that Higress integration is third-party
and not managed by the Knative community, as requested by reviewers.

Change-Id: I98d3454da8a8e4cef74ac5a88d8b0f3017426c15
Co-developed-by: Cursor <noreply@cursor.com>

Author: johnlanni

docs/versioned/install/README.md

@@ -101,9 +101,12 @@ If you don't have an ingress that meets the requirements, Knative provides [net-
 
     The Kubernetes [Gateway API](https://kubernetes.io/docs/concepts/services-networking/gateway/) (beta).
 
-- Higress
+- Higress (Third-party integration)
 
     A next-generation cloud-native gateway that integrates traffic management, security protection, and microservices capabilities. Higress provides enhanced traffic governance, authentication, WAF protection, and observability for Knative services with WASM plugin extensibility. See [Higress: A Best Practice for Knative Ingress Gateway](https://www.alibabacloud.com/blog/higress-a-best-practice-for-knative-ingress-gateway_600549).
+    
+    !!! note
+        This integration is not managed by the Knative community.
 
 ### Messaging plugins