New user onboarding

[bioshazard]

Might be interesting to add something like this https://introjs.com/

However, anyone that would happen upon the project would do so through the home page which explains the tool. And anyone linked a board can be explained by someone who came through the home page. Might just close this issue.

[xorgol]

Hi, I've just come across the project from a random Twitter link, I found the explanation of the tool itself to be quite clear, the problem is that I had no idea what Lean Coffee is. An explanation or a link to one might be useful.