message: docs: fix example header in singleton services guide to match styleguide
  Removes the ".0" from code header, as that doesn't match the
  recommended code style for service files names.
  fixes
  PR Close
diff: @@ -25,7 +25,7 @@ There are two ways to make a service a singleton in Angular:
  Beginning with Angular 6.0, the preferred way to create a singleton service is to set `providedIn` to `root` on the service's `@Injectable()` decorator. This tells Angular
  to provide the service in the application root.
  -<code-example path="providers/src/app/user.service.0.ts" header="src/app/user.service.0.ts" linenums="false"> </code-example>
  +<code-example path="providers/src/app/user.service.0.ts" header="src/app/user.service.ts" linenums="false"> </code-example>
  For more detailed information on services, see the [Services](tutorial/toh-pt4) chapter of the
  [Tour of Heroes tutorial](tutorial).
  