fix: command to run init-db (#160)

Signed-off-by: Abigail Clennell <[email protected]>

src/content/docs/ncea/level-2/flask/database.mdx

@@ -175,7 +175,7 @@ def create_app():
 As we have now integrated our database into our app we can now initialise it. To do this we can run the following command:
 
 ```bash
-$ flask init-db
+$ flask --app flaskapp init-db
 Initialized the database.
 ```