Fix auto-mitigate flag description (#14375)

Author: simanor

specification/monitor/resource-manager/Microsoft.Insights/stable/2018-04-16/scheduledQueryRule_API.json

@@ -606,7 +606,7 @@
         "autoMitigate": {
           "type": "boolean",
           "default": false,
-          "description": "The flag that indicates whether the alert should be automatically resolved or not. The default is true."
+          "description": "The flag that indicates whether the alert should be automatically resolved or not. The default is false."
         },
         "enabled": {
           "type": "string",