Fixup in README.md (#133)

* Fixup in README.md

I think there is a protocol conformance missing in the example.

* Update README.md

Co-authored-by: Adam Fowler <[email protected]>

---------

Co-authored-by: Adam Fowler <[email protected]>
Co-authored-by: Franz Busch <[email protected]>

Author: 3 people

README.md

@@ -40,7 +40,7 @@ Furthermore, the group will setup signal listeners for the configured signals an
 on each service.
 
 ```swift
-actor FooService {
+actor FooService: Service {
     func run() async throws {
         print("FooService starting")
         try await Task.sleep(for: .seconds(10))