added possible features

README.md

@@ -42,6 +42,10 @@ placing clue numbers, so every puzzle has a solution by construction.
 - [ ] Add some kind of zoom feature
    - Scroll wheel
    - and/or a ui button for zoom in/out
+
+### Possible Features
+- Keep local "high score" for each puzzle type
+
 ---
 
 ## Using the package locally (before it lands in nixpkgs)