Improve direct transfer contribution guide

Context

With Direct Transfer - Handle Vulnerabilities (#501466 - closed) @mbenayoun added vulnerability reports to direct transfer using direct transfer contribution guide. It's a first contribution of this type to direct transfer from outside of the groupimport and integrate.

We want to both celebrate that and learn from the experience on how we can improve the guide and make the collaboration of the contributors and the group, including PM and TW even easier.

This issue is to gather feedback and action it with updates to the direct transfer contribution guide and to the process of discovery of this opportunity and collaboration.

What can I do?

Create individual comments for every entry so that each item can have its own thread. Start your comment with an H2 heading which will be used as its title, and add the appropriate icon ahead of it to indicate which category it falls under:

## :thumbsup: Something that went well

## :thumbsdown: Something that didn't go well

## :bulb: Something we can improve

## :question: Something for discussion but not a clear good or bad event to improve upon