docs: Add API title to core concepts documentation and add a dependency injection example.

Author: CarLeonDev

website/src/content/docs/core_concepts/dependency_injection.mdx

@@ -17,6 +17,8 @@ Dependency injection offers several benefits.
 - **Inversion of Control**: It adheres to the principle of inversion of control, where the responsibility for object creation and management is delegated to Reactter. This results in improved code _modularity_, _reusability_, and _testability_.
 - **Simplified Code**: By offloading the responsibility of creating dependencies from individual classes, dependency injection simplifies code, allowing classes to focus more on their core functionality.
 
+## API
+
 Reactter provides the following dependencies injection mechanisms:
 
 - Hooks
@@ -243,11 +245,30 @@ void main() async {
   print('Count: ${counter?.count ?? 'Counter instance not found'}');
 }
 ```
-In this case, the countdown will work as before, but when trying to get the <HT>`Counter`</HT> instance to print itsvalue,
+In this case, the countdown will work as before, but when trying to get the <HT>`Counter`</HT> instance to print its value,
 the ouput will be _“Counter instance not found”_.
 This occurs because <HT>`Counter`</HT> was registered as  <HE>`DependencyMode.builder`</HE>(the default mode),
 so when it was deleted at the end of the countdown its registration was also deleted.
-If we want to get the <HT>`Counter`</HT> instance to print its value, we need to register using the <HE>`DependencyMode.singleton`</HE> mode.
+If we want to get the <HT>`Counter`</HT> instance to print its value, we need to register using the <HE>`DependencyMode.singleton`</HE> mode, looking like this:
+
+```dart title="main.dart" {7} collapse={8-15} "Rt.register" "Rt.create" "Rt.get" "DependencyMode.singleton" /counter(?!\\.)/ "counter?.count" /Counter(?!\u0060)(?! )/ /Countdown(?!\u0060)/ /(countdown) =/ "countdown.run"
+import 'package:reactter/reactter.dart';
+import 'countdown.dart';
+import 'counter.dart';
+
+void main() async {
+  // Register the `Counter` class as singleton mode with an initial value of 20
+  Rt.register(() => Counter(20), mode: DependencyMode.singleton);
+  // Create an instance of the `Countdown` class
+  final countdown = Rt.create(() => Countdown())!;
+  // Start the countdown
+  await countdown.run();
+  // Get the instance of the `Counter` class
+  final counter = Rt.get<Counter>();
+  // Try to print the current count value
+  print('Count: ${counter?.count ?? 'Counter instance not found'}');
+}
+```
 
 Let's now delve into the **modes** of dependency registration.
 

website/src/content/docs/core_concepts/event_handler.mdx

@@ -11,6 +11,8 @@ and coordination between various components within the application.
 Designed to ensure efficient state management and dependency injection,
 fostering a cohesive ecosystem where different parts of the application can interact harmoniously.
 
+## API
+
 Reactter offers the following event handler mechanisms:
 
 - Hooks

website/src/content/docs/core_concepts/hooks.mdx

@@ -20,6 +20,8 @@ import UseTextInputCode from '@/examples/custom_hook/lib/use_text_input.dart?raw
 
 Hooks are classes with the ability to use states and manage side effects. They are a fundamental concept in Reactter and are used to encapsulate logic that can be reused across the application.
 
+## API
+
 Reactter provider some hooks to manage the state and side effects of the application, which are:
 
 - <HT>[`UseState`](/reactter/hooks/use_state)</HT>

website/src/content/docs/core_concepts/rendering_control.mdx

@@ -20,6 +20,9 @@ import counterMainCode from '@/examples/counter/lib/main.dart?raw';
 
 In Flutter, efficient rendering control is essential for crafting high-performance, responsive, and scalable applications.
 Reactter provides a way to easily control the rendering of components in the widget tree behavior effortlessly, using the _**flutter_reactter**_ package.
+
+## API
+
 This package provides a collection of classes, widgets and some methods:
 
 - Classes
@@ -45,7 +48,7 @@ The rendering control in Reactter is based on two core concepts of Flutter:
 - **InheritedWidget**: This powerful mechanism efficiently shares data across the widget tree.
 Reactter extends this capability with the <HT>`RtProvider`</HT> widget, which stores dependencies using the dependency injection system.
 This allows descendant widgets to access these dependencies as needed.
-- **BuildContext Methods**: These methods facilitate dependency access and rendering control within the widget tree.
+- **BuildContext Extensions**: These methods facilitate dependency access and rendering control within the widget tree.
 Reactter widgets like <HT>`RtConsumer`</HT>, <HT>`RtSelector`</HT>, and <HT>`RtComponent`</HT> use these methods to observe dependencies or states.
 Whenever the dependency or any observed state undergoes a change, these widgets promptly trigger the rebuilding of the widget tree to reflect the updated state.
 

website/src/content/docs/core_concepts/state_management.mdx

@@ -10,6 +10,8 @@ import StateMethods from '@/content/docs/shareds/state_methods.mdx';
 State management is a critical aspect of any application.
 It allows you to manage the state of your application, and facilitates seamless tracking and handling of changes to it.
 
+## API
+
 Reactter provides a variety of mechanisms for state management, including classes, hooks, and methods:
 
 - Classes
@@ -33,7 +35,7 @@ Reactter provides a variety of mechanisms for state management, including classe
 Reactter's state management system is based on the concept of _reactivity_.
 Contrary to the prevailing notion that implementing reactive programming in Dart can be challenging,
 Reactter greatly simplifies this process.
-To dive into the concept, let's start by exploring what constitutes a state in Rt.
+To dive into the concept, let's start by exploring what constitutes a state in Reactter.
 
 ### State
 

website/src/content/docs/getting_started.mdx

@@ -3,7 +3,6 @@ title: Getting started
 description: A step-by-step guide to installing and how to use Reactter.
 ---
 
-import { Icon } from "astro-icon/components";
 import { Code } from "@astrojs/starlight/components";
 
 import reactterVersion from "@/data/reactter_version";