fix directory structure in api.html#packages

<script data-main="scripts/main" src="scripts/require.js"></script>

means directory structure should be:

project-directory/
  - project.html
  - cart/
    - main.js
  - store/
    - main.js
    - util.js
  - scripts/ # ADDED
    - main.js
    - require.js

Instead of:

project-directory/
  - project.html
  - cart/
    - main.js
  - store/
    - main.js
    - util.js
 - main.js # MOVED TO scripts/main.js
 - require.js # MOVED TO scripts/require.js