docs: add build system differential loading theory of operation overview
docs: add build system differential loading theory of operation overview

clydin/angular-cli,geofffilippi/angular-cli,Brocco/angular-cli,Brocco/angular-cli,beeman/angular-cli,catull/angular-cli,angular/angular-cli,manekinekko/angular-cli,ocombe/angular-cli,manekinekko/angular-cli,beeman/angular-cli,Brocco/angular-cli,filipesilva/angular-cli,geofffilippi/angular-cli,ocombe/angular-cli,angular/angular-cli,catull/angular-cli,angular/angular-cli,filipesilva/angular-cli,ocombe/angular-cli,Brocco/angular-cli,angular/angular-cli,geofffilippi/angular-cli,Brocco/angular-cli,catull/angular-cli,clydin/angular-cli,beeman/angular-cli,ocombe/angular-cli,beeman/angular-cli,filipesilva/angular-cli,filipesilva/angular-cli,catull/angular-cli,geofffilippi/angular-cli,ocombe/angular-cli,clydin/angular-cli,manekinekko/angular-cli,clydin/angular-cli