Improve documentation
Improve documentation

* condition for redirect is 403 not 404
* add note to remember to set region when bucket is not located in us-east-1
elidupuis/ember-cli-deploy-s3-index,elidupuis/ember-cli-deploy-s3-index,LevelbossMike/ember-cli-deploy-s3-index,ember-cli-deploy/ember-cli-deploy-s3-index,ember-cli-deploy/ember-cli-deploy-s3-index,elidupuis/ember-cli-deploy-s3-index,LevelbossMike/ember-cli-deploy-s3-index,LevelbossMike/ember-cli-deploy-s3-index,vitch/ember-cli-deploy-s3-index,vitch/ember-cli-deploy-s3-index