The trail supporters feature is based on the Vancouver area's "Trail Adoption Program" which pairs a trail builder with a corporate sponsor to work on an adopted trail throughout the year. The trail supporters feature can be used to list supporters of a trail or can list the builders & maintainers of the trail.
This feature gives some credit and exposure to those who support the trails. A supporter can be linked to a Pinkbike Places listing, Pinkbike user profile, or a special 'trail supporter' entity. A company logo can also be added to these links which are displayed on the trail's page, along with the special 'trail supporters' page for each region.
To add a trail supporter or maintainer, first edit the trail, and then look for the "Maintainers / Supporters" section near the bottom. You can add multiple supporters and specify which years those individuals supported the trail.
Each region additionally has a "Trail Supporters" page listing each trail with supporters:
Here is an example page showcasing the North Shore Trail Supporters.