Update docker requirements closes 949
Update docker requirements closes 949

Add some bits about the memory and file system requirements for the docker-compose build environment.
Phrozyn/MozDef,gdestuynder/MozDef,mozilla/MozDef,mpurzynski/MozDef,Phrozyn/MozDef,Phrozyn/MozDef,gdestuynder/MozDef,jeffbryner/MozDef,mpurzynski/MozDef,mpurzynski/MozDef,jeffbryner/MozDef,gdestuynder/MozDef,mpurzynski/MozDef,mozilla/MozDef,jeffbryner/MozDef,mozilla/MozDef,Phrozyn/MozDef,mozilla/MozDef,jeffbryner/MozDef,gdestuynder/MozDef