Update changelog.txt

Author: realSquidCoder

changelog.txt

@@ -35,6 +35,7 @@ Template for new versions:
 - `gui/settings-manager`: standing orders save/load now includes the reserved barrels setting
 - `gui/rename`: add overlay to worldgen screen allowing you to rename the world before the new world is saved
 - `gui/rename`: add overlay to the "Prepare carefully" embark screen that transparently fixes a DF bug where you can't give units nicknames or custom professions
+- `gui/notify`: new notification type: save reminder; appears 15 minutes after a save is created or loaded, click to be asked to quicksave
 
 ## Fixes
 - `fix/dry-buckets`: don't empty buckets for wells that are actively in use