add changelog entry for gui/notes

Author: myk002

changelog.txt

@@ -30,6 +30,7 @@ Template for new versions:
 - `devel/export-map`: export map tile data to a JSON file
 - `autocheese`: automatically make cheese using barrels that have accumulated sufficient milk
 - `gui/spectate`: interactive UI for configuring `spectate`
+- `gui/notes`: UI for adding and managing notes attached to tiles on the map
 
 ## New Features
 - `advtools`: new ``advtools.fastcombat`` overlay (enabled by default)  allows you to skip combat animations and the announcement "More" button by mashing the movement keys