[DOC] mail_base add not about todo in chat_manager.js

mail_base/README.rst

@@ -10,3 +10,7 @@ To use this module you need either install module that depends on it or create n
 Further information
 -------------------
 Due to odoo restrictions, module makes mail initialization again. That is browser loads emoji and other chat data twice. This is the only way to make Mail feature extendable.
+
+One can say, that the module do this todo from `addons/mail/static/src/js/chat_manager.js <https://github.com/odoo/odoo/blob/9.0/addons/mail/static/src/js/chat_manager.js#L57>`_
+
+    // to do: move this to mail.utils