Add extra desciption of Multiple ADs

Author: arnaudfroidmont

schema.yaml

@@ -168,7 +168,7 @@ variables:
   use_multiple_ads:
     type: boolean
     title: "Multiple ADs"
-    description: "Use multiple ADs in case of capacity constraints (Autoscaling Only)"
+    description: "Use multiple ADs in case of capacity constraints (Autoscaling Only) Autoscaling will try another AD upon failure."
     default: false
   ad:
     type: oci:identity:availabilitydomain:name