message: docs: fix typo in injected variable name
  The service injected is `ValueService`, however the name of the variable
  does not reflect that. It's actually confusing since it's the name of
  the `class` being created.
  PR Close
diff: @@ -37,8 +37,8 @@ export class ValueService {
  // #docregion MasterService
  @Injectable()
  export class MasterService {
  - constructor(private masterService: ValueService) { }
  - getValue() { return this.masterService.getValue(); }
  + constructor(private valueService: ValueService) { }
  + getValue() { return this.valueService.getValue(); }
  }
  // #enddocregion MasterService
  