message: docs(aio): remove services plurality
  remove services plurality for the sentence formation to be proper
  PR Close
diff: The Tour of Heroes `HeroesComponent` is currently getting and displaying fake data.
  After the refactoring in this tutorial, `HeroesComponent` will be lean and focused on supporting the view.
  -It will also be easier to unit-test with a mock services.
  +It will also be easier to unit-test with a mock service.
  ## Why services
  