New RFC: specify Waku2 ambient peer discovery protocol based on discv5

[kaiserd]

This issue is part of the Waku v2 discv5 Roadmap and tracks the editing of a new RFC specifying a Waku2 ambient discovery protocol as a version of Ethereum's Node Discovery Protocol v5 with minor changes.

The current implementation status is tracked in nim-waku #837.

Acceptance criteria

• RFC (in raw status) specifying WAKU2-DISCV5 (33/WAKU-DISCV5: Add first raw version #487)
  • directly promoted to draft status because we have a running implementation

Notes

When this RFC moves to draft status, 10/WAKU2 should be adapted to list the new ambient peer discovery method.