Update services.md (#20604)

Fixed a typo.

contribute/architecture/services.md

@@ -32,7 +32,7 @@ The `Init` method is used to initialize and configure the service to make it rea
 
 Every service needs to be registered with the application for it to be included in the service graph.
 
-To register a service, call the `registry.RegisterService` function in a `init` function within your package.
+To register a service, call the `registry.RegisterService` function in an `init` function within your package.
 
 ```go
 func init() {