Add license to bin scripts

[edmundmiller]

          I found this: https://nf-co.re/docs/checklists/reviews/pipeline_release_pr#do-local-code-and-modules

which says that bin scripts should have author and MIT license embedded. I don't have them in my pipeline either and not sure how new and mandatory this rule is; just leaving the link and comment here to figure it out

Originally posted by @vagkaratzas in #185 (comment)