Document the function of the release manager

[peternied]

The release manger duties should be documented so anyone can take on these responsibilities and drive an OpenSearch release.

Acceptance Criteria:

• Create a new top level markdown page 'ReleaseOwner.md`
• Document periodic tasks, such as daily, weekly
• Document meetings
• Document communication channels, such as GitHub, Slack and Email
• Document what the release manager is doing for the release over time
• The 1.3.0 release owner reviews this document

[abhinavGupta16]

The acceptance criteria has changed for the issue. We would not be creating ReleaseOwner.md now.

We'll now be adding the information on release_template.md and expanding the description on the issue itself