Add allow_multiple_targets to configuration documentation

source/_integrations/notify.rest.markdown

@@ -40,7 +40,7 @@ verify_ssl:
   type: boolean
   default: True
 authentication:
-  description:  Type of the HTTP authentication. `basic` or `digest`.
+  description: Type of the HTTP authentication. `basic` or `digest`.
   required: false
   default: basic
   type: string
@@ -69,6 +69,11 @@ target_param_name:
   description: Parameter name for the target.
   required: false
   type: string
+allow_multiple_targets:
+  description: Send all targets to the resource. By default, the notifier only sends the first one.
+  required: false
+  default: false
+  type: boolean
 data:
   description: Dictionary of extra parameters to send to the resource.
   required: false