Update ticket triaging documentation to mention new features process

[blighj]

​https://forum.djangoproject.com/t/volunteers-wanted-to-update-triage-workflow-docs/37937/
It was proposed on the above forum post to update the documentation for triaging tickets with information on the "new features process".
The ​https://github.com/django/new-features has been up and running for most of 2025 and there is now a new closed state needsnewfeatureprocess for tickets that are created on Trac that would be better starting their life on the new featuers board.

[Jacob Walls]

Thanks, James. Are you interested? Tickets with no owner seem to fly off the shelves these days :-)

[blighj]

Isn't it great that they are moving fast, I've done a first ​draft branch. If anyone wants to pick that up as a starting point and go from there, they are more than welcome. If no one has picked it up in a week or so I can do more work on it.
For the record the branch contains a new svg for the process diagram, and a description for the new closed flag.
Still to do is refine the description of the new flag and to generate a pdf of the svg, I'm not sure if there is a recommened django way of doing that bit.