docs: default acr script validation

docs/admin/config-guide/custom-scripts-config.md

@@ -363,3 +363,8 @@ For example, in our case; the command line is:
 ```
 
 That's all for `Custom Script` management with `CLI` feature.
+
+!!! Note
+
+If a custom script that is set as *Default authentication method* is disabled or deleted then the default authentication value will be removed.
+

docs/admin/config-guide/default-authentication-method-config.md

@@ -11,6 +11,28 @@ The Janssen Server allows administrators to set and manage the default
 authentication method for the authentication server.
 The Janssen Server provides multiple configuration tools to perform these tasks.
 
+!!! Note
+
+    Only one of the available authentication methods can be set as the default.
+    While setting the Default authentication method, the Janssen Server 
+    checks if the same authentication is available and active.
+
+    See 
+    [script documentation](custom-scripts-config.md#update-an-existing-custom-script) 
+    to know how to enable/disable authentication methods using custom scripts.
+
+
+    If the script is not active then the following error notification is 
+    returned by API.
+    ```{
+        "code": "400",
+        "message": "INVALID_ACR",
+        "description": "Authentication script {acr} is not active"
+    }
+    ```
+
+    Also, to understand how Janssen Server picks the authentication method *in absence* of default authentication method, refer to [ACR documentation](../auth-server/openid-features/acrs.md#flowchart---how-the-jans-as-derives-an-acr-value-for-a-user-session-)
+
 === "Use Command-line"
 
     Use the command line to perform actions from the terminal. Learn how to
@@ -142,4 +164,5 @@ authentication method.
 
 Janssen Server Configuration REST API exposes relevant endpoints for managing
 and configuring the Default Authentication Method. Endpoint details are published
-in the [Swagger document](./../reference/openapi.md).
+in the [Swagger document](./../reference/openapi.md).
+