make XXX lines come in sets of 3 :-) in Makefile.example

Makefile.example

@@ -1,6 +1,7 @@
 #!/usr/bin/env make
 #
-# XXX - Please remove these 2 XXX-ed comment lines - XXX
+# XXX - Please remove these 3 XXX-ed comment lines - XXX
+# XXX - Hint: Lines with XXX's in them should be removed are you read them and consider their suggestions - XXX
 # XXX - Change "an example Makefile" in the line below to a suitable and short 1-line title for your entry - XXX
 # prog - an example Makefile
 #