Change last-of-list function name

Update Last of List function name to `last` to avoid confusion.

snippets/last-of-list.md

@@ -3,5 +3,5 @@
 Return `arr.slice(-1)[0]`.
 
 ```js
-var initial = arr => arr.slice(-1)[0];
+var last = arr => arr.slice(-1)[0];
 ```