docs: fix typo (angular#26878)

PR Close angular#26878

Author: krantzinator

aio/content/guide/architecture-services.md

@@ -48,7 +48,7 @@ Similarly, use the `@Injectable()` decorator to indicate that a component or oth
 
 * An injector creates dependencies, and maintains a *container* of dependency instances that it reuses if possible.
 
-* A *provider* is an object that tell an injector how to obtain or create a dependency.
+* A *provider* is an object that tells an injector how to obtain or create a dependency.
 
 For any dependency that you need in your app, you must register a provider with the app's injector, 
 so that the injector can use the provider to create new instances.