Update readme

Author: shonfeder

README.org

@@ -1,7 +1,7 @@
 #+TITLE: 99 λProlog Problems
 
-An adaptation of the classic [[https://sites.google.com/site/prologsite/prolog-problems][99 Prolog Problems]] by [[https://sites.google.com/site/prologsite/author][Werner Hett]] to the
-higher-order logic programming in [[http://www.lix.polytechnique.fr/~dale/lProlog/][λProlog]].
+An adaptation of the classic [[https://sites.google.com/site/prologsite/prolog-problems][99 Prolog Problems]] by [[https://sites.google.com/site/prologsite/author][Werner Hett]] to higher-order
+logic programming in [[http://www.lix.polytechnique.fr/~dale/lProlog/][λProlog]].
 
 Before undertaking the problems, you may wish to review this slight adaptation
 of Hett's wonderful guidance:
@@ -39,4 +39,4 @@ Problems marked with three asterisks (***) are more difficult. You may need more
 time (i.e. a few hours or more) to find a good solution.
 #+end_src
 
-- [[file:problems/lists.org][Lists]]
+- [[file:problems/lists.org][Lists]] :: [[file:solutions/lists.mod][solutions]]