Fix MooseDocs search
Fix MooseDocs search

(closes #12162)

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