Merge branch 'fix-hold-the-ground-description' into 'master'

Fix Hold the Ground description

The physical save and cooldown values were swapped. See http://forums.te4.org/viewtopic.php?f=42&t=50773 .

I also removed a redundant '+' in the same description. I noticed that descriptions in general are inconsistent in whether they say "increase X by Y" vs "increase X by +Y". The latter seems redundant to me, so I removed it in this case. If you agree I could also do that for the other descriptions.

See merge request !625