Create a 'merge' test to join maps together. (#113)

src/koans/06_maps.clj

@@ -41,6 +41,9 @@
   "You can also create a new version with an entry removed"
   (= {__ __} (dissoc {1 "January" 2 "February"} 2))
 
+  "Create a new map by merging" 
+  (= {:a 1 :b 2 __ __} (merge {:a 1 :b 2} {:c 3}))
+
   "Often you will need to get the keys, but the order is undependable"
   (= (list __ __ __)
      (sort (keys { 2014 "Sochi" 2018 "PyeongChang" 2010 "Vancouver"})))