message: docs(aio): fix doc typo referring to `httpOptions`
  The variable name mention should match the actual tutorial code.
  PR Close
diff: @@ -287,7 +287,7 @@ The `HttpClient.put()` method takes three parameters
  The URL is unchanged. The heroes web API knows which hero to update by looking at the hero's `id`.
  The heroes web API expects a special header in HTTP save requests.
  -That header is in the `httpOption` constant defined in the `HeroService`.
  +That header is in the `httpOptions` constant defined in the `HeroService`.
  <code-example
  path="toh-pt6/src/app/hero.service.ts"
  