[#172237014]Correcting longstanding error in subnav
[#172237014]Correcting longstanding error in subnav

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