Updated pipeline documentation and results for mRNAseq

[Daniel-VM]

PR checklist

• [X] This comment contains a description of changes (with reason).
• [ ] Make sure your code lints (black and flake8).
• If a new tamplate was added make sure:
  • [x] Template's schema is added in templates/services.json.
  • [x] Template's pipeline's documentation in assets/reports/md/template.md is added.
  • [x] Results Documentation in assets/reports/results/template.md is updated.
• [x] CHANGELOG.md is updated.
• [ ] README.md is updated (including new tool citations and authors/contributors).
• [ ] If you know a new user was added to the SFTP, make sure you added it to templates/sftp_user.json

PR description

Updated pipeline documentation and results for mRNAseq.

partially BU-ISCIII/BU-ISCIII/issues/70

[Daniel-VM]

* Add the files description also to the results_rnaseq.md as they are delivered in the results folder

Do the description need to be added along with the images to assets/reports/results/rnaseq.md? or only the description?