update proxy ACL to also cover `cern.ch` and `opensciencegrid.org` domains#56

bedroge merged 3 commits intomultixscale:mainmultixscale/cvmfs-tutorial-hpc-best-practices:mainfrom

boegel:fix_proxy_aclboegel/cvmfs-tutorial-hpc-best-practices:fix_proxy_aclCopy head branch name to clipboard