Maybe consider alternative to deprecated DotTip

[kienstra]

The DotTip for additional CSS classes, added in #304, was recently deprecated in Gutenberg.

For now, I removed it in 440f50a. We got a report in the #support Slack channel of it causing an error.

Gutenberg suggests to use the Guide component instead.

But that doesn't look to have a way to disable the specific Guide in the future, like how the DotTip had a way to disable it.

And the Guide would appear for all users, even those who already disabled the specific DotTip.

We could probably implement something of our own, but it might be too complex.

[kienstra]

It looks like the Guide component can detect if all DotTips have been dismissed, like by clicking the 'disable tips' x from Luke's screenshot. But it can't detect if this specific tip was dismissed.