License two unlicensed help pages
Submitted by Gabor Kelemen
Link to original bug (#749157)
Description
The process-priority-what.page file is not listed in help/Makefile.am and this makes it not appear in the generated docs:
https://help.gnome.org/users/gnome-system-monitor/3.16/process-priority-change.html.en
links to it in this sentence:
(The system for managing the priority of processes is called nice.) but the link is broken.
Version: git master