docs: enhancement (#15)

Author: nank1ro

docs/src/content/docs/examples/basic.mdx

@@ -13,9 +13,6 @@ In particular, it shows how to create a provider, how to scope it, how to use it
 import 'package:disco/disco.dart';
 import 'package:flutter/material.dart';
 
-/// ---
-/// Model
-/// ---
 abstract class Model extends ChangeNotifier {
   void incrementCounter();
 
@@ -35,9 +32,6 @@ class ModelImplementation extends Model {
   }
 }
 
-/// ---
-/// Provider
-/// ---
 final modelProvider = Provider<Model>((context) => ModelImplementation());
 
 void main() {

docs/src/content/docs/index.mdx

@@ -7,6 +7,30 @@ description: Official documentation for Disco, a modern and simple library for s
 
 Disco is a library introducing a new concept of providers that operate differently from those already present in the Flutter ecosystem. It was developed to overcome the challenges and limitations in the context of dependency injection.
 
+## Usage
+
+### Creating a provider
+
+```dart
+final modelProvider = Provider((context) => Model());
+```
+
+### Providing a provider
+
+```dart
+ProviderScope(
+  providers: [modelProvider],
+  child: MyWidget(),
+)
+```
+
+### Retrieving a provider
+```dart
+final model = modelProvider.of(context);
+```
+
+You can retrieve a provider from any widget in the subtree of the `ProviderScope` where the provider has been provided.
+
 To get straight to the point, pros and cons are summarized below.
 
 ### Pros