Add nginx 1.15.11, remove nginx 1.15.10
Add nginx 1.15.11, remove nginx 1.15.10

for stack(s) cflinuxfs2, cflinuxfs3 [#165215032]

cf-identity/php-buildpack,cf-identity/php-buildpack,cf-identity/php-buildpack,cloudfoundry/php-buildpack,cf-identity/php-buildpack,cloudfoundry/php-buildpack,cf-identity/php-buildpack,cf-identity/php-buildpack,cf-identity/php-buildpack,cloudfoundry/php-buildpack,cloudfoundry/php-buildpack,cloudfoundry/php-buildpack,cloudfoundry/php-buildpack,cloudfoundry/php-buildpack