revert web build changes

README.md

@@ -41,6 +41,12 @@ Mileograph is a Flutter client for logging and analysing railway journeys. It le
   ```bash
   flutter build apk --release
   ```
+- Web (release + CanvasKit renderer for best performance/icons):  
+  ```bash
+  flutter build web --release --web-renderer canvaskit --tree-shake-icons
+  # or for local profiling:
+  flutter run -d chrome --profile --web-renderer canvaskit
+  ```
 
 ## Testing and linting
 - Static analysis: `flutter analyze`