Fixed grammar in comment.

dlib/image_transforms/hough_transform_abstract.h

@@ -239,7 +239,7 @@ namespace dlib
                           voted for any of the lines HP[i] in Hough space.  Note, however,
                           that if angle_window_size or radius_window_size are made so large
                           that HP[i] overlaps HP[j] for i!=j then the overlapping regions
-                          of Hough space are assign to HP[i] or HP[j] arbitrarily.
+                          of Hough space are assigned to HP[i] or HP[j] arbitrarily.
                           Therefore, all points in CONSTITUENT_POINTS are unique, that is,
                           there is no overlap in points between any two elements of
                           CONSTITUENT_POINTS.