(?) [Feature] More certificates

[sneko]

Hi!

I remember that when I started using your operator I enabled SSL for my ES cluster. Since I also enabled Cerebro and Kibana the operator has automatically generated appropriate certificates... but what about other client applications I would like to use?

It could be interesting that just by providing an array of strings to the ES cluster CRD the operator would create as much certificates as required.

What do you think, is it a good practice? Or should I manage that by myself?

Thank you