We used to have a ? icon beside all of the items in the filters which redirected users to a link.
I鈥檝e used my trackpad to draw a very, very poor version of what it used to look like 
The icons would only appear if there was a link defined here: fl-maps/categories.json at master 路 focallocal/fl-maps 路 GitHub
Please find, or recreate it and then tag me so i can update the links