docs: Document workaround about issue with object and embed tag.

Author: raffael-mnhn

README.rst

@@ -116,6 +116,12 @@ Optionally provide a fallback if there is no matching id/slug/instance::
     {% endsnippet_fragment %}
 
 
+Known issues
+------------
+
+When adding a snippet with the `object` or `embed` tag as root element, the CMS toolbar crashes, making any further editing of the page difficult or impossible. A workaround is to just put those elements inside a `div` tag.
+
+
 Running Tests
 -------------