Add a note that container can be used to inject styles to windows (#…

…2541)

* [DOC] Updated doc to add a cache option use-case

* remove changeset

Co-authored-by: Valerian Gonnot <valerian.gonnot@neovision.fr>
Co-authored-by: Mateusz Burzyński <mateuszburzynski@gmail.com>

packages/cache/README.md

@@ -53,7 +53,7 @@ The prefix before class names. It will also be set as the value of the `data-emo
 
 `HTMLElement`
 
-A DOM node that emotion will insert all of its style tags into. This is useful for inserting styles into iframes.
+A DOM node that emotion will insert all of its style tags into. This is useful for inserting styles into iframes or windows.
 
 ### `prepend`