Archive, multitagging, cleanup

Cleaned up the current snippets for consistency and minor problems, added multiple tags to most of them, archived a few.

snippets/tail.md

@@ -2,7 +2,7 @@
 
 Returns all elements in an array except for the first one.
 
-Return `arr.slice(1)` if the array's `length` is more than `1`, otherwise, return the whole array.
+Return `Array.slice(1)` if the array's `length` is more than `1`, otherwise, return the whole array.
 
 ```js
 const tail = arr => (arr.length > 1 ? arr.slice(1) : arr);