Update README.md

Author: kmicinski

prolog/README.md

@@ -1,10 +1,16 @@
 # Prolog examples and notes
 
+## Simple examples 
 - [`01-basics.pl`](01-basics.pl) -- An introduction to syntax and examples
 - [`02-math.pl`](02-math.pl) -- Mathematical builtins and `is` construct
 - [`03-lists.pl`](03-lists.pl) -- Manipulating lists 
 - [`04-hanoi.pl`](04-hanoi.pl) -- Towers of Hanoi
 - [`05-sort.pl`](05-sort.pl) -- Sorting lists
 - [`06-backtrack.pl`](06-backtrack.pl) -- Illustrating backtracking
+
+## Using the cut
 - [`cuts.pl`](cuts.pl) -- Explaining cuts
 - [`jedi.pl`](jedi.pl) -- Cuts and jedis
+
+## Larger examples 
+- [`cek.pl`](cel.pl) -- An implementation of the CEK machine in Prolog