Add instruction for adding a django app (cookiecutter#4944)

* feat(docs): add instruction for adding a django app

Following the the steps outlined in:
cookiecutter#4339 (comment)
this PR adds a "Creating Your First Django App" section to the docs
breifly expalins the file structure and outlines the steps to add a new
app.

* Update docs/developing-locally.rst

Co-authored-by: Bruno Alla <[email protected]>

* Update docs/developing-locally.rst

Co-authored-by: Bruno Alla <[email protected]>

---------

Co-authored-by: Bruno Alla <[email protected]>

docs/developing-locally.rst

@@ -96,6 +96,61 @@ First things first.
 .. _direnv: https://direnv.net/
 
 
+Creating Your First Django App
+-------------------------------
+
+After setting up your environment, you're ready to add your first app. This project uses the setup from "Two Scoops of Django" with a two-tier layout:
+
+- **Top Level Repository Root** has config files, documentation, `manage.py`, and more.
+- **Second Level Django Project Root** is where your Django apps live.
+- **Second Level Configuration Root** holds settings and URL configurations.
+
+The project layout looks something like this: ::
+
+    <repository_root>/
+    ├── config/
+    │   ├── settings/
+    │   │   ├── __init__.py
+    │   │   ├── base.py
+    │   │   ├── local.py
+    │   │   └── production.py
+    │   ├── urls.py
+    │   └── wsgi.py
+    ├── <django_project_root>/
+    │   ├── <name_of_the_app>/
+    │   │   ├── migrations/
+    │   │   ├── admin.py
+    │   │   ├── apps.py
+    │   │   ├── models.py
+    │   │   ├── tests.py
+    │   │   └── views.py
+    │   ├── __init__.py
+    │   └── ...
+    ├── requirements/
+    │   ├── base.txt
+    │   ├── local.txt
+    │   └── production.txt
+    ├── manage.py
+    ├── README.md
+    └── ...
+
+
+Following this structured approach, here's how to add a new app:
+
+#. **Create the app** using Django's ``startapp`` command, replacing ``<name-of-the-app>`` with your desired app name: ::
+
+    $ python manage.py startapp <name-of-the-app>
+
+#. **Move the app** to the Django Project Root, maintaining the project's two-tier structure: ::
+
+    $ mv <name-of-the-app> <django_project_root>/
+
+#. **Edit the app's apps.py** change ``name = '<name-of-the-app>'`` to ``name = '<django_project_root>.<name-of-the-app>'``.
+
+#. **Register the new app** by adding it to the ``LOCAL_APPS`` list in ``config/settings/base.py``, integrating it as an official component of your project.
+
+
+
 Setup Email Backend
 -------------------