update README, and consider repository finished (at least for now)

bench/build-get-prefix-string-set.sml

@@ -0,0 +1,20 @@
+structure BuildGetPrefixStringSet =
+struct
+  fun main () =
+    let
+      val endTrie =
+        Vector.foldl StringSet.insert StringSet.empty WordsList.words
+
+      val startTime = Time.now ()
+      val lst = StringSet.getPrefixList ("a", endTrie)
+      val finishTime = Time.now ()
+
+      val searchDuration = Time.- (finishTime, startTime)
+      val searchDuration = Time.toNanoseconds searchDuration
+      val searchDuration = LargeInt.toString searchDuration ^ " ns\n"
+    in
+      print searchDuration
+    end
+end
+
+val _ = BuildGetPrefixStringSet.main ()