[IMP] views: document attributes "class" and "js_class"

Part-of: odoo/documentation#3722

content/developer/reference/backend/views.rst

@@ -178,6 +178,15 @@ an impact on all view types.
 
 .. todo:: Views main content section, with field, group & separator ?
 
+* ``class``
+  optional string containing some classes to set on the root node of the view.
+
+* ``js_class``
+  optional component class to use to render the view.
+  If set, the ``js_class`` attribute will also be used to apply a css class to the
+  root node of the view. For example, if ``js_class`` is set to ``my-custom-kanban``,
+  then the class ``o_my-custom-kanban_view`` will be applied on the  root node.
+
 .. _reference/views/inheritance:
 
 Inheritance