[Release Notes] Add Dates and Link to Github

- Can dates of publication be added to the release notes?
- Can a link to the GitHub for the release be added?

Example:
On the release notes for [0.12.0](https://docs.pinot.apache.org/basics/releases/0.12.0):

Have the date "19 Jan 2023" at the top, and a line that says:

Source code for [Apache Pinot 0.12.0](https://github.com/apache/pinot/releases/tag/release-0.12.0) on GitHub

[Also let me know if there's a separate repo for Pinot docs I should put this in instead.]