My new labs-vagrant instance shows
Help for enabled roles
(run vagrant roles help in the directory where you installed MediaWiki-Vagrant to get help about enabling roles)
But labs-vagrant roles help doesn't work, it just prints a usage message.
I would love to get more info about available roles, I have no idea what e.g. the commons role does. If "roles help" command can't be implemented. can't be done, then at least Help:Labs-vagrant should tell me where the code for roles is so I can read their source.