update changelog for https://bugtracker.codiodev.com/issue/codio-1644 (#397)

Author: shajason

source/instructors/getstarted/support/changelog.rst

@@ -15,6 +15,7 @@ We do not report small bug fixes or issues that affect individual users, who we
 
 **July 2025**
 
+- `[I] [30th]`: If a student tries to log in when they have an uncompleted assignment in Single Login mode, they have the option to mark that assignment as complete.
 - `[F] [8th]`: Add :ref:`Blueprints for guide pages <blueprints>`
 - `[F] [7th]`: The Codio dashboard has been updated.