Update instructions and perhaps add Tip Jar?

[interactiveRob]

Woah! It was so hard to find an open source tool to accomplish the rolling numbers animation. Your CustomElement work made it easy to implement with no issues.

You should add a tip jar to your readme like https://www.buymeacoffee.com, I want to contribute.

Also I was able to figure out by looking at the demo that I just needed to manipulate the value attribute when I want the animation to start, but that may not be clear to others.

I might make a PR on the readme to help you update the instructions there. Thanks!

Feel free to close the issue after reading.