message: docs: fix typo from singular to plural spelling
  This commit fixes the spelling of the singular form
  of the word function to the plural spelling in
  packages/core/src/application_init.ts
  PR Close
diff: @@ -15,7 +15,7 @@ import {Inject, Injectable, InjectionToken, Optional} from './di';
  * A [DI token](guide/glossary#di-token "DI token definition") that you can use to provide
  * one or more initialization functions.
  *
  - * The provided function are injected at application startup and executed during
  + * The provided functions are injected at application startup and executed during
  * app initialization. If any of these functions returns a Promise, initialization
  * does not complete until the Promise is resolved.
  *
  