Right now we show when a variable is included in documentation.conf. Variables are included in that file for Toaster purposes: that has no impact on the builds themselves, so we should just remove that line from the variable history.
merged to master http://git.yoctoproject.org/cgit/cgit.cgi/poky/commit/?id=5301c59503e0d3fdc0080d80754ec66db40de46c
verified in master:ba8506ee342a1a579ceb309f3f50285eaad84f25