Where to find root-ca.pem for kibana ?

I’m getting error:

log [12:22:17.487] [error][elasticsearch] Request error, retrying HEAD https://localhost:9200/ => self signed certificate in certificate chain


when tried to run kibana 5.0 that read from ElasticSearch 5.0 with SearchGuard ssl.

The documentation mentioned about:

elasticsearch.ssl.ca: “/path/to/your/root-ca.pem”

The question is where can I find this root-ca.pem file ?

Inside folder elasticsearch-5.0.0-sg5/search-guard-ssl/example-pki-scripts/ca, there is root-ca.pem, but I’ve tried setting elasticsearch.ssl.ca with that file, it still doesn’t work.

Anything I miss here?