Update pricing.md to account for ephemeral sessions

Author: mbifeld

articles/cloud-shell/pricing.md

@@ -12,12 +12,11 @@ Cloud Shell is a free service. You only pay for the underlying Azure resources t
 
 ## Compute cost
 
-Azure Cloud Shell runs on a machine provided for free by Azure, but requires an Azure file share to
-use.
+Azure Cloud Shell runs on a machine provided for free by Azure. If you desire file persistance, Cloud Shell requires an Azure File Share.
 
 ## Storage cost
 
-Cloud Shell requires a new or existing Azure Files share to be mounted to persist files across
+Cloud Shell requires a new or existing Azure Files Share to be mounted to persist files across
 sessions. Storage incurs regular costs. For pricing information, see [Azure Files Pricing][01].
 
 ## Network costs