Publishing v3 alpha

[meatballhat]

I would like to add and push a v3.0.0-alpha tag in the v3-dev-main branch in the near future. This will allow projects to begin trying out the v3 API as described here.

go get github.com/urfave/cli/[email protected]

I realize that the v3 API is currently very similar to the v2 API, but larger breaking changes are coming soon. Please let us know what concerns or questions you may have!

[chkohner]

Is there a document outlining the design goals of v3? There are certainly a fair number of pain points we've been dealing with on v2, and it'd be nice to see if those are under consideration.

[dearchap]

See #833