docs: remove installation and numbering from discovery service

Author: vahidvdn

content/fundamentals/discovery-service.md

@@ -2,11 +2,8 @@
 
 The `DiscoveryService` is a utility provided by `@nestjs/core` that allows developers to dynamically discover providers, controllers, and other metadata within a NestJS application. This can be particularly useful for building plugins, decorators, or features that rely on runtime introspection.
 
-### Installation
 
-`DiscoveryService` is part of `@nestjs/core`, so it does not require separate installation. You can use it directly within your NestJS application.
-
-### Importing DiscoveryService and DiscoveryModule
+### Import Module & Service
 
 Before using the `DiscoveryService`, you need to import the `DiscoveryModule` in your module:
 
@@ -45,7 +42,7 @@ export class ExampleService {
 
 ### Use Cases
 
-#### 1. Discovering Providers
+#### Discovering Providers
 
 You can retrieve all registered providers in the application:
 
@@ -56,7 +53,7 @@ console.log(providers);
 
 Each provider object contains information about the instance, token, and metadata.
 
-#### 2. Discovering Controllers
+#### Discovering Controllers
 
 Retrieve all registered controllers:
 
@@ -65,7 +62,7 @@ const controllers = this.discoveryService.getControllers();
 console.log(controllers);
 ```
 
-#### 3. Finding Metadata
+#### Finding Metadata
 
 `DiscoveryService` can help find metadata attached to providers or controllers. This is useful when working with decorators that add metadata.