chore(app): add useful flutter aliases

app/CONTRIBUTING.md

@@ -11,11 +11,23 @@ Please also see the [contribution guide in the root folder](../CONTRIBUTING.md).
   - Run `dart pub get` to fetch all dart dependencies
   - Run `flutter pub get` to fetch all flutter dependencies and setup all
     generated code
-  - Run `flutter pub run build_runner build --delete-conflicting-outputs`
+  - Run `flutter pub run build_runner build --delete-conflicting-outputs` or
+    `flutter pub run build_runner watch --delete-conflicting-outputs` to
+    re-generate code upon file changes while developing
 
 You should now be able to run the app by opening the debug panel on the left and
 pressing the green triangle at the top (or using the shortcut <kbd>F5</kbd>).
 
+## Useful Shortcuts
+
+For (cleaning) generated code, you might want to add the following aliases to
+your shell configuration:
+
+```bash
+alias flutter-generate='flutter pub run build_runner build --delete-conflicting-outputs'
+alias flutter-clean='find . -maxdepth 20 -type f \( -name "*.inject.summary" -o -name "*.inject.dart" -o  -name "*.g.dart" \) -delete'
+```
+
 ## Architecture
 
 The app consists of multiple so-called modules. Our main modules correspond to