link fix

Author: mlhoop

articles/aks/private-clusters.md

@@ -127,4 +127,4 @@ The API server end point has no public IP address. Consequently, users will need
 [az-feature-list]: /cli/azure/feature?view=azure-cli-latest#az-feature-list
 [az-extension-add]: /cli/azure/extension#az-extension-add
 [az-extension-update]: /cli/azure/extension#az-extension-update
-[private-link-service]: ../private-link/private-link-service-overview
+[private-link-service]: https://docs.microsoft.com/azure/private-link/private-link-service-overview