Update libMesh doxyfile
Update libMesh doxyfile

refs #14499

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