sitemap feature: document
To create the clean URL, we will learn about the `document feature` of Sitemap
Sitemap let's you structure your website by allowing you to organize your files
in hierarchical manner ie. separate sections, subsections and TOC.
1. it helps to decouple the package organization and corresponding URLs.
So you can keep files as you wish in the package but URL still does not depend
on the path of the file.
2. It empowers the user to give a custom URL to the page
3. And That also helps to give a clean URL
4. Not only this, you can include a file more than once in the sitemap with