Loading root6

[maroozm]

This is regarding Quick start for STAR users given in the README:

I was not able to run this command:
spack load star-env-root6 target=x86_64

I had to first activate one of the listed env (spack env list) that has root6: spack env activate star-x86_64-root6
and at the end, loaded root6 by spack load star-env

Thanks