Elasticsearch Resource Does Not Support Volumes and volumeMounts

Add relevant sections to the templates and values file to allow for mounting of custom "volumes" and their associated "volumeMounts" to the Elasticsearch resource.

added elasticsearch kindenhancement statusdoing labels

changed iteration to Big Bang Iterations Apr 21, 2021 - May 4, 2021

changed milestone to %1.7.0

created merge request !38 (merged) to address this issue

mentioned in merge request !38 (merged)

added statusreview label and removed statusdoing label

closed with merge request !38 (merged)

mentioned in commit d84a935f

removed statusreview label