Adding --dry-run flag

fast-sim-and-analysis/FccFastSimGeneration.md

@@ -68,7 +68,7 @@ The Gaudi steering file needs to activate the `GaudiTool` that interfaces `Pythi
 An example of steering file can be found at [pythia.py](https://raw.githubusercontent.com/HEP-FCC/k4Gen/main/k4Gen/options/pythia.py). The steering file runs the minimal set of algorithms to run Pythia8 and produce an output in `EDM4hep` format:
 ```
 $ wget https://raw.githubusercontent.com/HEP-FCC/k4Gen/main/k4Gen/options/pythia.py
-$ k4run pythia.py 
+$ k4run --dry-run pythia.py
  -->  Pythia8 -->  HepMCToEDMConverter -->  StableParticles -->  out
 [...]
 ```