revert subscripton id to the former description

Author: adklinge

specification/monitor/resource-manager/Microsoft.Insights/preview/2017-05-01-preview/subscriptionDiagnosticsSettings_API.json

@@ -325,7 +325,7 @@
       "in": "path",
       "required": true,
       "type": "string",
-      "description": "The Azure subscription Id."
+      "description": "The subscription Id."
     },
     "NameParameter": {
       "name": "name",