docs: add project structure

docs/structure.md

@@ -0,0 +1,46 @@
+# Project Structure
+
+In a Selva project, you need to define at least the `application`.
+
+It can be a Python module or package and represents the main code of the project.
+Any controllers or services defined under it will be discovered and registered
+in the dependency injection context.
+
+If your project is small, you can just define the `aplication.py` module, but you
+can have any structure you need inside the `application` package.
+
+For example:
+
+```
+project/
+└── application/
+    ├── __init__.py
+    ├── controller/
+    │   ├── __init__.py
+    │   ├── public/
+    │   │   ├── __init__.py
+    │   │   ├── about.py
+    │   │   ├── home.py
+    │   │   └── product.py
+    │   └── private/
+    │       ├── __init__.py
+    │       ├── category.py
+    │       ├── customer.py
+    │       └── product.py
+    ├── model/
+    │   ├── __init__.py
+    │   ├── category.py
+    │   ├── customer.py
+    │   └── product.py
+    ├── repository/
+    │   ├── __init__.py
+    │   ├── category.py
+    │   ├── customer.py
+    │   └── product.py
+    └── service/
+        ├── __init__.py
+        ├── category.py
+        ├── customer.py
+        ├── email.py
+        └── product.py
+```

mkdocs.yml

@@ -43,6 +43,7 @@ markdown_extensions:
 nav:
   - Selva: index.md
   - tutorial.md
+  - structure.md
   - controllers.md
   - routing.md
   - templates.md