make github repo work as helm repo

[KlavsKlavsen]

Fixes #692

Description of changes:
Adds docs of 2 commands to run, when changing version in Chart.yaml - to build Helm repo version and update the index.yaml needed by Helm to use this github repo as a Helm repo directly.

[peterzhuamazon]

Thanks @KlavsKlavsen we are reviewing this PR. Will get you updated once the review is done.

Thanks.

[peterzhuamazon]

Hi @KlavsKlavsen we have introduced (OpenSearch)[https://opensearch.org] and would really appreciate if this PR can be opened there once we migrate the Helm there.

Will inform here once we complete the migration.

Thanks.

[KlavsKlavsen]

@peterzhuamazon I'll gladly do so.. but why have the helm chart for opendistro-es not been moved over as well? or the elasticsearch helm chart? I see no chart in the opensearch repo.

[bbarani]

@KlavsKlavsen We just created a public repo to host the devops-related code, that includes Helm charts as well. Please feel free to take a stab at migrating the existing helm chart code and raise a PR for review. Thanks a lot for your contribution!

[peterzhuamazon]

Hi @KlavsKlavsen we have moved to OpenSearch (opensearch.org)
And we just merged the 1st version of Helm there opensearch-project/opensearch-devops#4
Could you close this PR and migrate there? Thanks.