message: docs(aio): fix typo in NgModule FAQs
  Fix Fix typo 'added' to 'add' in the 'Why does lazy loading create a child injector' section.
diff: @@ -615,7 +615,7 @@ Once the application begins, the app root injector is closed to new providers.
  Time passes and application logic triggers lazy loading of a module.
  Angular must add the lazy-loaded module's providers to an injector somewhere.
  -It can't added them to the app root injector because that injector is closed to new providers.
  +It can't add them to the app root injector because that injector is closed to new providers.
  So Angular creates a new child injector for the lazy-loaded module context.
  