Update scheduler.yml

I propose to add a comment in the example scheduler.yml file to identify a pitfall which caused me a bit of trouble.
 Minor modifications
Merge pull request #34 from rousseab/patch-1

Update scheduler.yml
Merge branch 'master' of https://github.com/gmatteo/abipy
 Minor changes
 Benchmark for MPI-FFT
 Add script for benchmarking G0W0
 New version of bench_pfft
 abirun.py: select first flow in cwd if path is not given + pass fermi level to Ebands.to_pymatgen
Updated for Moab

Added MoabJobFile option to AbinitInput
Fixed for Moab

imported MoabJobFile