Clarify comments in new teams unit test

Author: Damian Rouson

src/tests/unit/teams/teams_subset.f90

@@ -22,8 +22,8 @@ program teams_subset
           min_image = [initial_team_image, this_image()]
           call co_min(min_image)
         end team
-        call assert( all(min_image==1), "minimum image number in team is 1" )
-        call assert( all(max_image==[num_images(), 2]), "team maximum images numbers is num_images() or 2")
+        call assert( all(min_image==1), "minimum image number in team 1 is 1" )
+        call assert( all(max_image==[num_images(), 2]), "maximum image numbers on team 1 is num_images() or 2")
       end block
     end if