Update Readme

Author: FranzBusch

README.md

@@ -28,9 +28,41 @@ and to your application target, add `ServiceLifecycle` to your dependencies:
 
 ###  Using ServiceLifecycle
 
-You can find the documentation on how to use ServiceLifecycle over [here](https://swiftpackageindex.com/swift-server/swift-service-lifecycle/main/documentation/lifecycle).
+Below is a short usage example however you can find detailed documentation on how to use ServiceLifecycle over [here](https://swiftpackageindex.com/swift-server/swift-service-lifecycle/main/documentation/lifecycle).
 
-Do not hesitate to get in touch as well, over on https://forums.swift.org/c/server.
+ServiceLifecycle consists of two main building blocks. First, the `Service` protocol and secondly
+the `ServiceGroup`. As a library or application developer you should model your long-running work
+as services that implement the `Service` protocol. The protocol only requires a single `func run() async throws`
+method to be implemented.
+Afterwards, in your application you can use the `ServiceGroup` to orchestrate multiple services.
+The group will spawn a child task for each service and call the respective `run` method in the child task.
+Furthermore, the group will setup signal listeners for the configured signals and trigger a graceful shutdown
+on each service.
+
+```swift
+actor FooService {
+    func run() async throws {
+        print("FooService starting")
+        try await Task.sleep(for: .seconds(10))
+        print("FooService done")
+    }
+}
+
+@main
+struct Application {
+    static func main() async throws {
+        let service1 = FooService()
+        let service2 = FooService()
+        
+        let serviceGroup = ServiceGroup(
+            services: [service1, service2],
+            configuration: .init(gracefulShutdownSignals: [.sigterm])
+        )
+        try await serviceGroup.run()
+    }
+}
+
+```
 
 ## Security