add extra line after error message

Author: slobodanadamovic

x-pack/plugin/security/cli/src/main/java/org/elasticsearch/xpack/security/cli/HttpCertificateCommand.java

@@ -1054,6 +1054,7 @@ private static List<String> readKeyUsage(Terminal terminal, List<String> default
                     for (String keyUsageName : CertGenUtils.KEY_USAGE_MAPPINGS.keySet()) {
                         terminal.println(" - " + keyUsageName);
                     }
+                    terminal.println("");
                     return null;
                 }
                 resolvedKeyUsages.add(keyUsage);