docs/managing/add-platform: add section about docker-registry and multiple nodes
docs/managing/add-platform: add section about docker-registry and multiple nodes

mderaldo/tsuru,RichardKnop/tsuru,cezarsa/tsuru,gwmoura/tsuru,ggarnier/tsuru,ArxdSilva/tsuru,4eek/tsuru,ggarnier/tsuru,hcxiong/tsuru,ArxdSilva/tsuru,Endika/tsuru,tsuru/tsuru,tuxmonteiro/tsuru,hcxiong/tsuru,ggarnier/tsuru,4eek/tsuru,kgrvamsi/tsuru,cgvarela/tsuru,RichardKnop/tsuru,ArxdSilva/tsuru,guilhermebr/tsuru,RichardKnop/tsuru,firebitsbr/tsuru,tsuru/tsuru,guilhermebr/tsuru,hugoantunes/tsuru,cezarsa/tsuru,cezarsa/tsuru,Endika/tsuru,guilhermebr/tsuru,cezarsa/tsuru,kgrvamsi/tsuru,4eek/tsuru,ArxdSilva/tsuru,ggarnier/tsuru,firebitsbr/tsuru,guilhermebr/tsuru,jblancett/tsuru,jblancett/tsuru,tsuru/tsuru,cgvarela/tsuru,gciotta/tsuru,cgvarela/tsuru,firebitsbr/tsuru,gwmoura/tsuru,gciotta/tsuru,mderaldo/tsuru,hugoantunes/tsuru,kgrvamsi/tsuru,jblancett/tsuru,Endika/tsuru,tuxmonteiro/tsuru,mderaldo/tsuru,tsuru/tsuru,gwmoura/tsuru,hcxiong/tsuru,tuxmonteiro/tsuru,gciotta/tsuru