remove non-exisiting file from subnav
remove non-exisiting file from subnav

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