Simplified "Environment-Modules" section in getting started guide. (#6410)
Simplified "Environment-Modules" section in getting started guide. (#6410)

Fixes #2440

The "Getting started" guide should be short and sweet. This commit
simplifies the "Environment-Modules" section pruning:

 - outdated / wrong suggestions as noted in #2440
 - uncommon setups that are better treated in a reference guide
EmreAtes/spack,mfherbst/spack,krafczyk/spack,tmerrick1/spack,matthiasdiener/spack,LLNL/spack,LLNL/spack,EmreAtes/spack,matthiasdiener/spack,iulian787/spack,krafczyk/spack,matthiasdiener/spack,iulian787/spack,LLNL/spack,krafczyk/spack,EmreAtes/spack,mfherbst/spack,mfherbst/spack,tmerrick1/spack,krafczyk/spack,tmerrick1/spack,LLNL/spack,matthiasdiener/spack,iulian787/spack,LLNL/spack,iulian787/spack,matthiasdiener/spack,iulian787/spack,tmerrick1/spack,EmreAtes/spack,mfherbst/spack,krafczyk/spack,EmreAtes/spack,mfherbst/spack,tmerrick1/spack