Redmine

Every tracker should have an optional description. Best case this would be realized as an optional link into a Wiki-page, but an admin should also be able to link to an arbitrary page.
The user of a ticket shall be able to click on this link when he's selecting the tracker for a certain ticket. So he would get assistance for how and what to use directly in the ticket itself.

Redmine could be adapted much quicker in organizations if the process could be designed in a more self-explaining manner.