add source install details to main readme
add source install details to main readme

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