PowhegControl: 23.6.41 fixes + doc update - AGENE-2314 and AGENE-2315
requested to merge atlas-physics/pmg/mcexperts/powheg-experts/athena:Powheg_few23.6.41Fixes into main
This fixes the bug reported in AGENE-2314 (gg4l, error messages from Powheg fortran code which should be warnings) and AGENE-2315 (ggHH_SMEFT, update of python function in Powheg process code).
Also I added some infos in the documentation, regarding multicore and integration grids.