Category with html extension

Hello:

Is there a way to permalink the category page as:
yourwebsite-name.com/category-name/category-name.html

In other words, I wish to add the .html extension to my category page.
For example, on my new website https://www.GuruMai.com,

https://www.gurumai.com/category/internet-marketing
which displays one of the category page should now display:
https://www.gurumai.com/category/internet-marketing/internet-marketing.html