title: How to declare the welcome file (e.g. index.html) in app.yaml
body: <p>In Java, the web.xml might contain some <code>&lt;welcome-file&gt;</code> elements. I am trying to do something equivalent in python with no luck. </p>
  
  <pre><code>application: wk
  version: 1
  runtime: python
  api_version: 1
  
  handlers:
  - url: /
    static_dir: docs
  
  welcome_files:
  - index.html
  </code></pre>
  
  <p>Any thoughts? I get an error that "welcome_files" is not understood. </p>