Remove legacy reference code and document.
Remove legacy reference code and document.

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