Update FccFastSimGeneration.md

[pkoppenb]

k4run pythia.py -h is likely a typo. To get the line displayed you need to remove -h. In my case the piping into head causes a logging error (both at Nikhef and CERN).

[kjvbrt]

Hi @pkoppenb,

the -h argument for k4run no longer shows the algorithm chain, instead one can use --dry-run.

Side note: ATM when k4run output is piped to head it will generage errors you observe. This PR key4hep/k4FWCore#186 attemps to fix the issue, but for the time being let's remove all uses of head.

[pkoppenb]

Thanks Juraj. Looks good.

For a bit of context: the tutorial was used with a bunch of 35 Nikhef PhD students. It went very well.