Updates README.md to clarify runOnPostBuild uses
Updates README.md to clarify runOnPostBuild uses

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