Make tooltip persist on click instead of on hover during visualization

[joshjms]

We should have the option to make the tooltip persist on the screen when the associated block is clicked. It is very difficult to keep hovering while scrolling down when the contents of the tooltip is long (see below image). For additional context, the image below is screenshot by inspecting the tooltip element and manually setting display: block.

Reference: etcd-io/etcd#19901, etcd-io/etcd#19933

[anishathalye]

Great idea; we could also show a bigger tooltip on click rather than hover. Will add this to my todo list (also happy to accept a pull request if anyone wants to work on the visualization/index.js that is a little bit spaghetti code 🙃).

[joshjms]

Thanks, I'll try to work on it!