config.json in trackler-2.1.0.28

- old
+ new

@@ -531,9 +531,16 @@
             "Transforming",
             "Dictionaries"
          ]
       },
       {
+         "slug":"book-store",
+         "difficulty":5,
+         "topics":[
+            "Recursion"
+         ]
+      },
+      {
          "slug":"nth-prime",
          "difficulty":6,
          "topics":[
             "Optional values",
             "Algorithms",
\ No newline at end of file