Add resources to Nextflow collection

[GiorgiaMori]

1. https://midnighter.github.io/nextflow-gotchas/
   from Arthur - one of my go-to places when I run into a bug I can’t immediately diagnose and as a general debugging resource. I think some of the information isn’t relevant with recent Nextflow updates but there’s a lot of people who don’t run on the latest versions still

2. Blog post on managing test data using DVC