Remove link to removed devguide/services/managed.html doc from index
Remove link to removed devguide/services/managed.html doc from index

bridgetkromhout/docs-book-cloudfoundry,swisscom/docs-appcloud-book,cwest/docs-book-cloudfoundry,cwest/docs-book-cloudfoundry,shalako/docs-book-cloudfoundry,shalako/docs-book-cloudfoundry,cwest/docs-book-cloudfoundry,swisscom/docs-appcloud-book,cwest/docs-book-cloudfoundry,cloudfoundry/docs-book-cloudfoundry,cloudfoundry/docs-book-cloudfoundry,shalako/docs-book-cloudfoundry,bridgetkromhout/docs-book-cloudfoundry,shalako/docs-book-cloudfoundry,bridgetkromhout/docs-book-cloudfoundry,cloudfoundry/docs-book-cloudfoundry,bridgetkromhout/docs-book-cloudfoundry,cloudfoundry/docs-book-cloudfoundry,swisscom/docs-appcloud-book,swisscom/docs-appcloud-book