Design, document and improve the license and license rules contribution processes

## Context

The license and license rules contribution processes is not working efficiently.

Today this is based on a combo of
- issues entered here and in the licensedb static repo
- PR here and entries in DejaCode license app
- sync of the license DB between here and DejaCode
- sync of the license DB with SPDX new releases

## Problem
Also:
- There are over 200+ licenses issues pending
- the process is not efficient and slow
- it is not easy for contributors to contribute

## Solution

We need to design, document and improve the license and license rules contribution processes.

Some areas to consider:
- https://github.com/aboutcode-org/scancode-toolkit/issues/4953
- https://github.com/aboutcode-org/scancode-toolkit/issues/5110
- move the licenses and rules in their own repo
- make the DejaCode license app accessible to any vetted contributor
- Combine efforts with OSI