Add plugin pack concept to architecture doc
Add plugin pack concept to architecture doc

kpfefferle/ember-cli-deploy,ember-cli-deploy/ember-cli-deploy,duizendnegen/ember-cli-deploy,duizendnegen/ember-cli-deploy,achambers/ember-cli-deploy,ember-cli/ember-cli-deploy,ember-cli/ember-cli-deploy,ember-cli/ember-cli-deploy,ember-cli-deploy/ember-cli-deploy,kpfefferle/ember-cli-deploy,achambers/ember-cli-deploy,ember-cli-deploy/ember-cli-deploy,LevelbossMike/ember-cli-deploy,LevelbossMike/ember-cli-deploy