Add support for BubbleChart - Update index.js

[orim181]

Add support for BubbleChart - based on https://github.com/ankane/chartkick/blob/master/vendor/assets/javascripts/chartkick.js

[orim181]

@ankane It looks straightforward but let me know otherwise. Thanks!

[orim181]

For those that want to use the bubble chart, I published a fork on npm (sadly) until this PR is approved - https://www.npmjs.com/package/@orim181/vue-chartkick

[ankane]

Hey @orim181, thanks for the PR! Bubble charts are still experimental in Chartkick.js, which is why they're not available here.

[orim181]

Thanks @ankane. I could understand.

Do you think it helps to introduce it anyway under the same “experimental” badge to help make your wrapper library more consistent with the underlying Chartkick.js library?

Might be useful to those who’ve wanted to use it in its experimental form. Just a thought.