fix link in postinstall message
fix link in postinstall message

nyimbi/tilemill,paulovieira/tilemill-clima,tizzybec/tilemill,nyimbi/tilemill,florianf/tileoven,MappingKat/tilemill,Zhao-Qi/tilemill,Zhao-Qi/tilemill,nyimbi/tilemill,mbrukman/tilemill,tizzybec/tilemill,Teino1978-Corp/Teino1978-Corp-tilemill,tilemill-project/tilemill,paulovieira/tilemill-clima,mbrukman/tilemill,mbrukman/tilemill,tizzybec/tilemill,nyimbi/tilemill,fxtentacle/tilemill,Teino1978-Corp/Teino1978-Corp-tilemill,paulovieira/tilemill-clima,Zhao-Qi/tilemill,Teino1978-Corp/Teino1978-Corp-tilemill,fxtentacle/tilemill,mbrukman/tilemill,Zhao-Qi/tilemill,MappingKat/tilemill,tilemill-project/tilemill,florianf/tileoven,MappingKat/tilemill,Zhao-Qi/tilemill,paulovieira/tilemill-clima,Teino1978-Corp/Teino1978-Corp-tilemill,tizzybec/tilemill,nyimbi/tilemill,MappingKat/tilemill,paulovieira/tilemill-clima,Teino1978-Corp/Teino1978-Corp-tilemill,fxtentacle/tilemill,MappingKat/tilemill,florianf/tileoven,tizzybec/tilemill,tilemill-project/tilemill,fxtentacle/tilemill,fxtentacle/tilemill,mbrukman/tilemill