Add a missing comma.

usr.bin/find/find.1

@@ -262,7 +262,7 @@ is used with
 .Xr cpio 1
 to process files that are contained in directories with unusual permissions.
 It enures that you have write permission while you are placing files in a
-directory then sets the directory's permissions as the last thing.
+directory, then sets the directory's permissions as the last thing.
 .It Ic -empty
 True if the current file or directory is empty.
 .It Ic -exec Ar utility Op Ar argument ... ;