yaml in Google App Engine with index.html

I'm building a website, I have no index.py how to I ensure index.html comes up when I type in my http开发者_JAVA技巧://localhost:8080/?

I have in yaml

- url: /
  static_files: static/HTML
  upload: static/HTML/index.html

but this does not seem to work.

---

Your static_files directive needs to include the full path to the file:

static_files: static/HTML/index.html