command/agent: proper flag docs on event-handler
command/agent: proper flag docs on event-handler

yonglehou/serf,samaitra/serf,curtiszimmerman/serf,mapuri/serf,FollowMyDev/serf,jmptrader/serf,FollowMyDev/serf,patrickviet/serf,pmenglund/serf,mbrukman/serf,yonglehou/serf,gnawhleinad/serf,gnawhleinad/serf,dalehamel/serf,FollowMyDev/serf,gnawhleinad/serf,hashicorp/serf,mapuri/serf,curtiszimmerman/serf,minhkiller/serf,jmptrader/serf,mapuri/serf,mapuri/serf,jmptrader/serf,samaitra/serf,minhkiller/serf,FollowMyDev/serf,curtiszimmerman/serf,curtiszimmerman/serf,mbrukman/serf,mbrukman/serf,samaitra/serf,curtiszimmerman/serf,hashicorp/serf,gnawhleinad/serf,dalehamel/serf,hashicorp/serf,pmenglund/serf,pmenglund/serf,patrickviet/serf,hashicorp/serf,patrickviet/serf,dalehamel/serf,mbrukman/serf,hashicorp/serf,minhkiller/serf,jmptrader/serf,samaitra/serf,patrickviet/serf,curtiszimmerman/serf,yonglehou/serf,FollowMyDev/serf,yonglehou/serf,gnawhleinad/serf,gnawhleinad/serf,FollowMyDev/serf,mapuri/serf,jmptrader/serf,minhkiller/serf,samaitra/serf,minhkiller/serf,patrickviet/serf,dalehamel/serf,dalehamel/serf,patrickviet/serf,mapuri/serf,mbrukman/serf,minhkiller/serf,yonglehou/serf,samaitra/serf,yonglehou/serf,dalehamel/serf,jmptrader/serf,mbrukman/serf,pmenglund/serf,pmenglund/serf,pmenglund/serf