Write a function words_ending_with(wordlist, tail) that behaves as follows.
The argument wordlist is a list of strings, while the argument tail is
a string. words_ending_with(wordlist, tail) returns a list consisting
of those strings in wordlist that end with tail. If none of the
strings in wordlist end with tail, it returns the empty list.
The order of list elements in the list returned by the function should match the order
of their occurrence in wordlist.
