Nice spinner/loading indicator
**Describe the requested icon**
First of all want to say a huge THANK YOU for releasing this library, this is by far the most nice looking and perfectly designed icon set. Please keep maintaining it, it will for sure become more and more popular!

As per icon request, would be nice to have some nice loading indicator that can be animated with infinite rotation in CSS.

**Screenshots**
Something like this:

<img width="269" alt="Screenshot 2021-06-17 at 17 02 48" src="https://user-images.githubusercontent.com/17024224/122424880-5c417a00-cf8f-11eb-9c5d-2cc564c2a2e4.png">

