DOC: Add PR tags and licensing to CONTRIBUTING.md
DOC: Add PR tags and licensing to CONTRIBUTING.md

oesteban/fmriprep,oesteban/preprocessing-workflow,oesteban/fmriprep,oesteban/preprocessing-workflow,poldracklab/preprocessing-workflow,poldracklab/fmriprep,poldracklab/fmriprep,oesteban/fmriprep,poldracklab/preprocessing-workflow,poldracklab/fmriprep