Fix: Use manage.py instead of django-admin to start app for better project context safety

[hasdajustin]

The current documentation (or example) uses the command django-admin startapp <app_name> to create a new Django app. While this works, it may cause unexpected issues when executed outside the Django project directory or virtual environment.
To ensure the app is created within the correct project context (especially when settings need to be loaded or project-specific paths are required), it is recommended to use:
python manage.py startapp <app_name>
This command ensures that the Django project’s environment and settings are correctly loaded during app creation, preventing potential configuration issues.