Added lisp code to the .md file

Author: Trashtalk217

contents/thomas_algorithm/thomas_algorithm.md

@@ -127,6 +127,8 @@ You will find this algorithm implemented [in this project](https://scratch.mit.e
 [import, lang:"crystal"](code/crystal/thomas.cr)
 {% sample lang="kotlin" %}
 [import, lang:"kotlin"](code/kotlin/thomas.kt)
+{% sample lang="lisp" %}
+[import, lang:"lisp"](code/clisp/thomas.lisp)
 {% endmethod %}
 
 <script>