add docstring for establishment by slug

apps/establishment/views/back.py

@@ -102,6 +102,36 @@ class EmployeePositionsListView(generics.ListAPIView):
 
 
 class EstablishmentRUDView(EstablishmentMixinViews, generics.RetrieveUpdateDestroyAPIView):
+    """
+    Establishment by slug
+
+    Implements get, update, delete methods
+
+    **GET**
+    ```
+    EstablishmentRUDView GET method
+    Implement getting Establishment by slug
+    ```
+
+    **PUT**
+    ```
+    EstablishmentRUDView PUT method
+    Implement update of Establishment by slug
+    ```
+
+    **PATCH**
+    ```
+    EstablishmentRUDView PATCH method
+    Implement partial update of Establishment by slug
+    ```
+
+    **DELETE**
+    ```
+    EstablishmentRUDView DELETE method
+    Implement delete Establishment by slug
+    ```
+
+    """
     lookup_field = 'slug'
     serializer_class = serializers.EstablishmentRUDSerializer
     permission_classes = get_permission_classes(