add hint for certificate troubleshooting with openssl

Author: corporatemax

services/log-management.html.md.erb

@@ -138,7 +138,7 @@ You can create a syslog drain service and bind apps to it using Cloud Foundry Co
     $ awk 'NF {sub(/\r/, ""); printf "%s\\n",$0;}' cert.pem | sed 's/\\n$//' | tr -d '\n'
     </pre>
 
-    The `cf create-user-provided-service` command will accept any json payload without validating the certificates or credentials while creating the syslog drain. In older syslog agent version there is no error message for wrong certificates or credentials - you can only validate in your target log service if your syslog drain was configured correctly.
+    The `cf create-user-provided-service` command will accept any json payload without validating the certificates or credentials while creating the syslog drain. In older syslog agent version there is no error message for wrong certificates or credentials - you can only validate in your target log service if your syslog drain was configured correctly. To troubleshoot your certificates, you can use the openssl commandline tool.
 
     For more information, see [User-provided service instances](./user-provided.html).