Add note about storing untitled albums in Google Takeout documentation

docs/google-takeout.md

@@ -14,6 +14,7 @@ Google takeout structure is complex and not documented. Some information may be
     - Hopefully, the JSON has a Trashed field.
   - The "Failed Videos" contains unreadable videos
   - Untitled albums are named in the user's language and a number: Untitled, Sin título, Sans Titre 
+  - All untitled albums can be stored into the same folder. Therefore it's impossible to rebuild original albums.
 
 ## Images have a JSON companion file
   - the JSON contains some information on the image