HOWTO force hdgeant4 to decay particles in certain channels

1/ Prior to hdgeant4 step by running evtgen after generation as a postprocessor.

https://halldweb.jlab.org/wiki/index.php/HOWTO_Use_EvtGen_to_simulate_particle_decays_in_GlueX

2/ At hdgeant4 step by adding these lines to control.ini

Please look here: https://groups.google.com/g/gluex-software/c/n0NQMOX7bC4/m/IKUwwKDQAwAJ

TO-DO: summarize thread and show an example