Feature: Auto-show which-key after a timeout

[MattSturgeon]

I was confused for a while when first using this plugin because I was typing C-b (prefix) and expecting which-key to appear after a short delay, similar to which-key.nvim.

Eventually I realized that the configured "keybind" are intended to activate which-key itself, however it'd be great to also have an auto-display option.

If this is difficult or impossible, perhaps the README could be improved to more clearly explain usage?

[alexwforsythe]

I've added a quickstart section to the README--right after installation--to hopefully clear things up.

I honestly wasn't aware of this feature because I don't use neovim, but it sounds like a good one! I'm open to working on it but can't give any estimate of when I'll start or how long it'll take. In the meantime, contributions are welcome.