add template var for defaulting ert to ha[#143605687]
add template var for defaulting ert to ha[#143605687]

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