Make passing a token optional

[jgooge-vso]

The RKE2 ansible automation will generate a token if one isn't explicitly defined. It'd be nice if this automation was configured the same way.

[dereknola]

Please see #294, as this was already asked for and answered. I ran into a problem of bootstrapping later server nodes with the token generated on the first. More broadly, this repo is maintain by me as a low priority. Hopefully it works and doesn't have bugs, but I don't have the bandwidth to add new features. If you need other features, I am happy to review and merge PRs or I would suggest looking at the Other Projects Shoutouts in the README.