update documentations

Author: fr33m0nk

src/data_structures/queue/list.clj

@@ -15,6 +15,8 @@
     (drop-last 1 queue)))
 
 (defn peek-queue
+  "this implementation is more performant than using `last` or `reverse`
+  they both traverse the entire collection whereas count is stored on the PersistenceList object"
   [queue]
   (when-not (empty? queue)
     (nth queue (dec (count queue)))))