When a user submits a module and they don't put the correct SCM URL format, the following error is returned The submitted scmurl git://dist-git.example.com/modules/perl-App-cpanminus is not valid. We should tell the user what the format should look like and that the git identifier is missing.

Additionally, if the modulemd file is not named correctly in the repo, MBS will just return an error that says The SCM repository doesn't contain a modulemd file. We should mention what modulemd file name MBS is expecting and couldn't find.