Add -iface option to agent help.
Add -iface option to agent help.

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