DOC: Update surface preproc description
DOC: Update surface preproc description

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