adding mailing list to main readme

[anuragprat1k]

Description

As in title

Fixes # (issue)

Type of change

Please check the options that are relevant.

• Bug fix (non-breaking change that fixes an issue)
• Proposes a change (non-breaking change that isn't necessarily a bug)
• Refactor
• New feature (non-breaking change that adds a new functionality)
• Breaking change (fix or feature that would break some existing functionality downstream)
• This is a unit test
• Documentation only change

Type of requested review

• I want a thorough review of the implementation.
• I want a high level review.
• I want a deep design review.