Better integration with GitHub "template/generate" feature?

[alexanderankin]

Hi asdf-vm maintainers,

Figured that we could document the decision for using a setup.bash custom script rather than having people just plugin in a couple of files (tool name, tool test, gh repo) and then no script is necessary at all and people could painlessly keep pulling in new changes, the way the feature is supposed to work? I was personally not the least surprised i could have been (https://en.wikipedia.org/wiki/Principle_of_least_astonishment) while reading/running the setup.bash file.