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
  - scripts/ # ADDED, nest under /scripts
    - cart/
      - main.js
    - store/
      - main.js
      - util.js
    - main.js
    - require.js

Instead of:

- project-directory/
  - project.html
  - cart/
    - main.js
  - store/
    - main.js
    - util.js
 - main.js
 - require.js