Create releases (or at least tags!) for releases since 3.0.0

[oliverlockwood]

It's a bit confusing that if you browse https://github.com/stepio/coffee-boots the "Releases" section links to 3.0.0 as the most recent release, and even hitting "Tags" in that view doesn't show anything later. The Readme also suggests version 2.2.0.

I had to go digging to find out that I should be using 4.0.0 for SB3 support; it would be nicer to make this more discoverable for others. Hopefully not too onerous a request 😃