exercises/practice/anagram: add an append with instructions about the order of the return values

Author: IsaacG

exercises/practice/anagram/.docs/instructions.append.md

@@ -1,3 +1,5 @@
 # Instructions append
 
 The result should be a string with anagrams separated by a comma (e.g., `"hello,world"`).
+
+You must return the anagrams in the same order as they are listed in the candidate words.