remove 'pre-release' refs from the config.yml
remove 'pre-release' refs from the config.yml

swisscom/docs-appcloud-book,swisscom/docs-appcloud-book,cloudfoundry/docs-book-cloudfoundry,cloudfoundry/docs-book-cloudfoundry,swisscom/docs-appcloud-book,cloudfoundry/docs-book-cloudfoundry,swisscom/docs-appcloud-book,cloudfoundry/docs-book-cloudfoundry