a few tweaks to event listener documentation
a few tweaks to event listener documentation

yuhangwang/pv,yuhangwang/pv,biasmv/pv,biasmv/pv,Traksewt/pv,biasmv/pv,biasmv/pv,CyrusBiotechnology/pv,Traksewt/pv,CyrusBiotechnology/pv,yuhangwang/pv,yuhangwang/pv,CyrusBiotechnology/pv,CyrusBiotechnology/pv,Traksewt/pv,Traksewt/pv