Minor suggestion on how to build Singularity images
The current singularity tutorial is an awesome, self-contained example on how to build a singularity image, but I stumbled at two points when I tried to have one build.
The information that one needs to have group membership in the singulars group is buried in the comments of a script. I think it would help to have a disclaimer about this in the README of the example.
The README encourages to change the sl.def as needed, and the submit file, if the repo is cloned anywhere else but the default location ~/htcondor-templates/singularity. I think it would also be helpful to notify users in the README and in the comments of singularity.sh that the git clone call needs to be modified. Else, one can adjust .def files all they want, and still only build the default minimal example that's showcased in this example.
ping @m.wierzba for thoughts. I'm happy to PR a suggestion - let me know :)