GEODE-1759: Improve geode-site/website/README.md
GEODE-1759: Improve geode-site/website/README.md

Clarify what needs to happen on which branch and in which
directory to update the Apache Geode website.

smgoller/geode,PurelyApplied/geode,davinash/geode,prasi-in/geode,PurelyApplied/geode,davebarnes97/geode,masaki-yamakawa/geode,PurelyApplied/geode,smanvi-pivotal/geode,masaki-yamakawa/geode,davebarnes97/geode,jdeppe-pivotal/geode,pdxrunner/geode,pivotal-amurmann/geode,jdeppe-pivotal/geode,jdeppe-pivotal/geode,deepakddixit/incubator-geode,davinash/geode,pdxrunner/geode,smanvi-pivotal/geode,charliemblack/geode,smanvi-pivotal/geode,charliemblack/geode,davebarnes97/geode,deepakddixit/incubator-geode,davinash/geode,pivotal-amurmann/geode,shankarh/geode,pdxrunner/geode,prasi-in/geode,davinash/geode,smgoller/geode,smanvi-pivotal/geode,masaki-yamakawa/geode,smgoller/geode,deepakddixit/incubator-geode,PurelyApplied/geode,pivotal-amurmann/geode,smgoller/geode,davebarnes97/geode,pivotal-amurmann/geode,masaki-yamakawa/geode,prasi-in/geode,deepakddixit/incubator-geode,shankarh/geode,jdeppe-pivotal/geode,deepakddixit/incubator-geode,charliemblack/geode,masaki-yamakawa/geode,davebarnes97/geode,davinash/geode,pdxrunner/geode,pivotal-amurmann/geode,masaki-yamakawa/geode,smanvi-pivotal/geode,shankarh/geode,PurelyApplied/geode,prasi-in/geode,davebarnes97/geode,jdeppe-pivotal/geode,deepakddixit/incubator-geode,smgoller/geode,davinash/geode,pdxrunner/geode,masaki-yamakawa/geode,davinash/geode,jdeppe-pivotal/geode,PurelyApplied/geode,shankarh/geode,pdxrunner/geode,smgoller/geode,PurelyApplied/geode,charliemblack/geode,charliemblack/geode,shankarh/geode,smgoller/geode,prasi-in/geode,jdeppe-pivotal/geode,deepakddixit/incubator-geode,pdxrunner/geode,davebarnes97/geode