multi-plasticity paper added to citing.md
multi-plasticity paper added to citing.md

Fixes #13765

sapitts/moose,bwspenc/moose,nuclear-wizard/moose,SudiptaBiswas/moose,idaholab/moose,dschwen/moose,lindsayad/moose,permcody/moose,andrsd/moose,laagesen/moose,SudiptaBiswas/moose,sapitts/moose,jessecarterMOOSE/moose,laagesen/moose,nuclear-wizard/moose,idaholab/moose,milljm/moose,laagesen/moose,dschwen/moose,harterj/moose,idaholab/moose,dschwen/moose,andrsd/moose,laagesen/moose,idaholab/moose,andrsd/moose,milljm/moose,andrsd/moose,SudiptaBiswas/moose,harterj/moose,nuclear-wizard/moose,bwspenc/moose,bwspenc/moose,harterj/moose,idaholab/moose,andrsd/moose,bwspenc/moose,harterj/moose,SudiptaBiswas/moose,harterj/moose,milljm/moose,bwspenc/moose,jessecarterMOOSE/moose,YaqiWang/moose,milljm/moose,sapitts/moose,jessecarterMOOSE/moose,lindsayad/moose,dschwen/moose,nuclear-wizard/moose,SudiptaBiswas/moose,YaqiWang/moose,permcody/moose,jessecarterMOOSE/moose,sapitts/moose,lindsayad/moose,milljm/moose,laagesen/moose,lindsayad/moose,lindsayad/moose,permcody/moose,YaqiWang/moose,permcody/moose,jessecarterMOOSE/moose,sapitts/moose,dschwen/moose,YaqiWang/moose