I see two identical listings under http://wiki.ros.org/navigation#Tutorials which lead to similar places (but not identical?), which I found because I went to http://ros.org/wiki/turtlebot_navigation/Tutorials and found it blank for jade and kinetic.

The first page is using a wiki search macro, not regular text that is easy to fix.

Beyond the solution to those problems, is there a place beyond here, or making a comment on the page itself (using markup to hide the text, or make it visible for everyone), or is it an issue on the project page of the project that is being documented?