debian: update short and long description to match README
debian: update short and long description to match README

blablacar/exabgp,fugitifduck/exabgp,fugitifduck/exabgp,benagricola/exabgp,dneiter/exabgp,blablacar/exabgp,benagricola/exabgp,benagricola/exabgp,fugitifduck/exabgp,earies/exabgp,dneiter/exabgp,dneiter/exabgp,earies/exabgp,earies/exabgp,blablacar/exabgp