Add explanation to README
Add explanation to README

Thanks @designerham
TheoChevalier/bedrock,glogiotatidis/bedrock,alexgibson/bedrock,sylvestre/bedrock,CSCI-462-01-2017/bedrock,ericawright/bedrock,jgmize/bedrock,gerv/bedrock,sgarrity/bedrock,sgarrity/bedrock,sgarrity/bedrock,kyoshino/bedrock,glogiotatidis/bedrock,jpetto/bedrock,MichaelKohler/bedrock,ericawright/bedrock,analytics-pros/mozilla-bedrock,craigcook/bedrock,mkmelin/bedrock,MichaelKohler/bedrock,craigcook/bedrock,jgmize/bedrock,kyoshino/bedrock,hoosteeno/bedrock,ericawright/bedrock,glogiotatidis/bedrock,TheJJ100100/bedrock,hoosteeno/bedrock,TheoChevalier/bedrock,CSCI-462-01-2017/bedrock,pascalchevrel/bedrock,sgarrity/bedrock,TheJJ100100/bedrock,kyoshino/bedrock,MichaelKohler/bedrock,alexgibson/bedrock,Sancus/bedrock,mozilla/bedrock,mkmelin/bedrock,schalkneethling/bedrock,analytics-pros/mozilla-bedrock,Sancus/bedrock,kyoshino/bedrock,craigcook/bedrock,analytics-pros/mozilla-bedrock,hoosteeno/bedrock,flodolo/bedrock,glogiotatidis/bedrock,TheJJ100100/bedrock,jgmize/bedrock,TheJJ100100/bedrock,CSCI-462-01-2017/bedrock,analytics-pros/mozilla-bedrock,alexgibson/bedrock,sylvestre/bedrock,sylvestre/bedrock,MichaelKohler/bedrock,jgmize/bedrock,TheoChevalier/bedrock,pascalchevrel/bedrock,schalkneethling/bedrock,pascalchevrel/bedrock,craigcook/bedrock,CSCI-462-01-2017/bedrock,mozilla/bedrock,schalkneethling/bedrock,flodolo/bedrock,Sancus/bedrock,ericawright/bedrock,TheoChevalier/bedrock,alexgibson/bedrock,mozilla/bedrock,gerv/bedrock,jpetto/bedrock,jpetto/bedrock,gerv/bedrock,pascalchevrel/bedrock,sylvestre/bedrock,jpetto/bedrock,Sancus/bedrock,hoosteeno/bedrock,flodolo/bedrock,mkmelin/bedrock,gerv/bedrock,flodolo/bedrock,mozilla/bedrock,mkmelin/bedrock,schalkneethling/bedrock