doc(install): add details about installation
doc(install): add details about installation

add info about installing docker.io, virtualenv and docker-composer
akintolga/superdesk-aap,fritzSF/superdesk,amagdas/superdesk,ioanpocol/superdesk-ntb,hlmnrmr/superdesk,pavlovicnemanja92/superdesk,akintolga/superdesk-aap,darconny/superdesk,superdesk/superdesk-aap,pavlovicnemanja/superdesk,marwoodandrew/superdesk,ancafarcas/superdesk,ancafarcas/superdesk,plamut/superdesk,marwoodandrew/superdesk,mugurrus/superdesk,mdhaman/superdesk-aap,sivakuna-aap/superdesk,sivakuna-aap/superdesk,superdesk/superdesk,ioanpocol/superdesk,marwoodandrew/superdesk-aap,superdesk/superdesk-ntb,thnkloud9/superdesk,Aca-jov/superdesk,marwoodandrew/superdesk-aap,sivakuna-aap/superdesk,vied12/superdesk,fritzSF/superdesk,sivakuna-aap/superdesk,ioanpocol/superdesk,marwoodandrew/superdesk,plamut/superdesk,plamut/superdesk,petrjasek/superdesk-ntb,vied12/superdesk,sivakuna-aap/superdesk,thnkloud9/superdesk,superdesk/superdesk,akintolga/superdesk-aap,pavlovicnemanja92/superdesk,ioanpocol/superdesk,amagdas/superdesk,fritzSF/superdesk,vied12/superdesk,akintolga/superdesk,verifiedpixel/superdesk,mdhaman/superdesk-aap,verifiedpixel/superdesk,hlmnrmr/superdesk,marwoodandrew/superdesk-aap,petrjasek/superdesk-ntb,Aca-jov/superdesk,fritzSF/superdesk,fritzSF/superdesk,mugurrus/superdesk,superdesk/superdesk-aap,marwoodandrew/superdesk,superdesk/superdesk-aap,marwoodandrew/superdesk,amagdas/superdesk,verifiedpixel/superdesk,superdesk/superdesk-ntb,amagdas/superdesk,superdesk/superdesk-aap,superdesk/superdesk,superdesk/superdesk-ntb,mdhaman/superdesk,superdesk/superdesk-ntb,pavlovicnemanja92/superdesk,akintolga/superdesk,plamut/superdesk,sjunaid/superdesk,marwoodandrew/superdesk-aap,liveblog/superdesk,Aca-jov/superdesk,sjunaid/superdesk,gbbr/superdesk,mdhaman/superdesk,liveblog/superdesk,thnkloud9/superdesk,petrjasek/superdesk-ntb,darconny/superdesk,akintolga/superdesk,akintolga/superdesk,petrjasek/superdesk,ioanpocol/superdesk-ntb,pavlovicnemanja/superdesk,mdhaman/superdesk-aap,petrjasek/superdesk,akintolga/superdesk,pavlovicnemanja92/superdesk,akintolga/superdesk-aap,pavlovicnemanja92/superdesk,gbbr/superdesk,pavlovicnemanja/superdesk,petrjasek/superdesk,mdhaman/superdesk-aap,petrjasek/superdesk-ntb,vied12/superdesk,liveblog/superdesk,gbbr/superdesk,amagdas/superdesk,superdesk/superdesk,pavlovicnemanja/superdesk,verifiedpixel/superdesk,petrjasek/superdesk,ioanpocol/superdesk-ntb,liveblog/superdesk,mugurrus/superdesk,hlmnrmr/superdesk,sjunaid/superdesk,vied12/superdesk,darconny/superdesk,liveblog/superdesk,plamut/superdesk,verifiedpixel/superdesk,mdhaman/superdesk,ancafarcas/superdesk