message: docs: fix typo in http.md
  PR Close
diff: @@ -358,7 +358,7 @@ subscribes without a callback.
  The bare `.subscribe()` _seems_ pointless.
  In fact, it is essential.
  -Merely calling `HeroService.addHero()` **does not initiate the DELETE request.**
  +Merely calling `HeroService.deleteHero()` **does not initiate the DELETE request.**
  <code-example
  path="http/src/app/heroes/heroes.component.ts"
  