Update cache-best-practices-kubernetes.md

Update range of problematic ports for Istio

Author: shpathak-msft

articles/azure-cache-for-redis/cache-best-practices-kubernetes.md

@@ -31,7 +31,7 @@ If your Azure Cache for Redis client application runs on a Linux-based container
 
 ## Potential connection collision with _Istio/Envoy_
 
-Currently, Azure Cache for Redis uses ports 15000-15019 for clustered caches to expose cluster nodes to client applications. As documented [here](https://istio.io/latest/docs/ops/deployment/requirements/#ports-used-by-istio), the same ports are also used by _Istio.io_ sidecar proxy called _Envoy_ and could interfere with creating connections, especially on port 15006.
+Currently, Azure Cache for Redis uses ports 15xxx for clustered caches to expose cluster nodes to client applications. As documented [here](https://istio.io/latest/docs/ops/deployment/requirements/#ports-used-by-istio), the same ports are also used by _Istio.io_ sidecar proxy called _Envoy_ and could interfere with creating connections, especially on port 15001 and 15006.
 
 When using _Istio_ with an Azure Cache for Redis cluster, consider excluding the potential collision ports with an [istio annotation](https://istio.io/latest/docs/reference/config/annotations/).