add docstring for establishment subtype by id

apps/establishment/views/back.py

@@ -638,7 +638,30 @@ class EstablishmentSubtypeListCreateView(generics.ListCreateAPIView):
 
 
 class EstablishmentSubtypeRUDView(generics.RetrieveUpdateDestroyAPIView):
-    """Establishment subtype retrieve/update/destroy view."""
+    """
+    Establishment subtype retrieve/update/destroy view.
+
+    **GET**
+    ```
+    Implement establishment subtype object getting method.
+    ```
+
+    **PUT**
+    ```
+    Implement establishment subtype update method.
+    ```
+
+    **PATCH**
+    ```
+    Implement establishment subtype partial update method.
+    ```
+
+    **DELETE**
+    ```
+    Implement establishment subtype delete method.
+    ```
+
+    """
     serializer_class = serializers.EstablishmentSubTypeBaseSerializer
     queryset = models.EstablishmentSubType.objects.select_related('default_image')
     permission_classes = get_permission_classes()