Add missing setup step to docs. Fixes #290.

Author: SteveSandersonMS

README.md

@@ -70,7 +70,8 @@ Also in this repo, [the `samples` directory](https://github.com/aspnet/JavaScrip
 
  * Clone this repo
  * Change directory to the same you want to run (e.g., `cd samples/angular/MusicStore`)
- * Restore dependencies (run `dotnet restore` and `npm install`)
+ * Restore dependencies (run `dotnet restore` and `npm install`).
+   * If you're trying to run the Angular 2 "Music Store" sample, then also run `gulp` (which you need to have installed globally). None of the other samples require this.
  * Run the application (`dotnet run`)
  * Browse to [http://localhost:5000](http://localhost:5000)