Block the PR emission if the PR description has not yet been changed

[sledigabel]

A suggestion from my teammate @lnascimentosilva shortly after using turbolift for the first time:

It would make sense to block the create-prs or at least ask for confirmation if the REAME.md file containing the PR description has not been modified yet.
The rationale is that users while finding their feet with turbolift may not realise they are filing a legit PR to a bunch of repos.

[Dan7-7-7]

This might be less of an issue once we enable updating PR descriptions - but I still think it's a good idea.