Another polyfill to add for older browsers

[brentrobbins]

Thanks for this create library. It works great!

I am using it for a project that requires IE11 support, so following your note I added the Intersection Observer polyfill. That did fix the Intersection Observer, however IE11 was also triggering an error for the CustomEvent. So I found a nice polyfill for that (https://github.com/kumarharsh/custom-event-polyfill) which did the trick. So I propose adding another note for this polyfill to help support older browsers.

[mciastek]

Looks like a great idea. I think that the best place to include information about polyfill is Events section in docs. What do you think?

[brentrobbins]

Hi @mciastek that's exactly where I was thinking too.