demo-starter projects: Make them templates

[matevz]

Github seems to offer a new type of repositories called "templates" that are meant to be forked and the built upon: https://docs.github.com/en/repositories/creating-and-managing-repositories/creating-a-repository-from-a-template

I saw this type of example here https://github.com/HashWarlock/erc-8004-ex-phala

Consider setting all of our demo-starter-* and demo-rofl-starter repositories as such.