regent: Update README.
regent: Update README.

sdalton1/legion,StanfordLegion/legion,StanfordLegion/legion,StanfordLegion/legion,StanfordLegion/legion,StanfordLegion/legion,sdalton1/legion,sdalton1/legion,sdalton1/legion,sdalton1/legion,StanfordLegion/legion,sdalton1/legion,StanfordLegion/legion,StanfordLegion/legion