Adding readme with link to a repo containing a comprehensive multiagent postgreSQL data management example (#6443)

## Why are these changes needed?

Requesting to add a new example folder under Python samples so that
AutoGen(0.4+) users can easily find this comprehensive example of using
agents and Groupchats to build a multi-agent data management system for
Azure postgreSQL. Readme contains link to a repo with comprehensive
multiagent postgreSQL data management example

## Related issue number

N/A

## Checks
N/A (only a readme file)
- [ ] I've included any doc changes needed for
<https://microsoft.github.io/autogen/>. See
<https://github.com/microsoft/autogen/blob/main/CONTRIBUTING.md> to
build and test documentation locally.
- [ ] I've added tests (if relevant) corresponding to the changes
introduced in this PR.
- [ ] I've made sure all auto checks have passed.

Co-authored-by: Mehrsa Golestaneh <mgolestaneh@microsoft.com>
Co-authored-by: Eric Zhu <ekzhu@users.noreply.github.com>