feat(assistance): Categorised Knowledge base articles

!43 #10

docs/projects/centurion_erp/development/forms.md

@@ -27,6 +27,30 @@ All forms must meet the following requirements:
 
     - Any filtering of a fields `queryset` is to filter the existing `queryset` not redefine it. i.e. `field[<field name>].queryset = field[<field name>].queryset.filter()`
 
+- validating fields where the validation requires access to multiple fields is done inside the form class using function `clean`
+
+    ``` py
+
+    def clean(self):
+            
+        cleaned_data = super().clean()
+
+        # begin example
+        responsible_user = cleaned_data.get("responsible_user")
+        responsible_teams = cleaned_data.get("responsible_teams") example
+
+
+        if not responsible_user and not responsible_teams:
+
+            raise ValidationError('A Responsible User or Team must be assigned.')
+        # end example
+
+        # your validation after `super()` call
+
+        return cleaned_data
+
+    ```
+
 
 ## Abstract Classes
 

docs/projects/centurion_erp/development/models.md

@@ -33,6 +33,11 @@ All models must meet the following requirements:
 
 - No `queryset` is to return data that the user has not got access to. _see [queryset()](./api/models/tenancy_object.md#tenancy-object-manager)_
 
+- Single Field validation is conducted if required.
+
+    !!! danger "Requirement"
+        Multi-field validation, or validation that requires access to multiple fields must be done within the [form class](./forms.md#requirements).
+
 
 ## History