Define the support details in SUPPORT.md

**Is your feature request related to a problem? 
No

**Describe the solution you'd like**
Define the support doc and reference from the README with the following,
- Support SLA for issues and PRs (I.e. -“ issues will get a reply in 48 hours, PR reviews 72 hours”)
- How to get in touch… GitHub only (issues for questions), or email, slack, discord….
- any other relevant support details.