Add documentation about db updates

README.md

@@ -181,6 +181,24 @@ Could not determine the dependencies of task ':unifiedpush_android:compileReleas
 
 Resolution: Ensure you have a valid Java 8 installation on your machine.
 
+## Database
+
+Thunder uses the [Drift database](https://drift.simonbinder.eu/) package (a wrapper around SQLite) to store information about the user's accounts, favorites, anonymous subscriptions, and user labels.
+
+If you happen to work on a contribution which involves updating the database schema, you can follow these steps.
+
+1. Update schema version in `lib\core\database\database.dart`
+2. Add new tables/columns in `lib\core\database\tables.dart`
+3. Export schema
+	- `dart run drift_dev schema dump lib/core/database/database.dart drift_schemas/`
+4. Update migrations
+    -  `dart run drift_dev schema steps drift_schemas/ lib/core/database/schema_versions.dart`
+5. Go back to `lib\core\database\database.dart` and implement the migration function
+6. Update the auto-generated db table models
+	- `dart run build_runner build`
+7. Reformat the auto-generated files
+    - `dart format --set-exit-if-changed -l 200 lib`
+
 ## Conventions
 
 While there are no specific conventions that must be followed, do try to follow best practices whenever possible.