Add max_rancher_version labels to istio charts

proposed/istio/v1.0.0/questions.yml

+rancher_max_version: 2.2.99
 categories:
 - Microservice 
 - Service mesh 

proposed/istio/v1.0.1/questions.yml

+rancher_max_version: 2.2.99
 categories:
 - Microservice 
 - Service mesh 

proposed/istio/v1.0.5/app-readme.md

-# Istio
+# Istio [deprecated]
 
 [Istio](https://istio.io/) is an open platform for providing a uniform way to integrate microservices, manage traffic flow across microservices, enforce policies and aggregate telemetry data.