added some text to the challenge 08-coding-interview-questions

seed/challenges/08-coding-interview-questions-and-take-home-assignments/coding-interview-algorithm-questions.json

@@ -98,7 +98,7 @@
       "id": "a3f503de51cf954ede28891d",
       "title": "Symmetric Difference",
       "description": [
-        "Create a function that takes two or more arrays and returns an array of the <dfn>symmetric difference</dfn> (<code>&xutri;</code> or <code>&oplus;</code>) of the provided arrays.",
+        "Create a function that takes two or more arrays and returns an array of the iterative <dfn>symmetric difference</dfn> (<code>&xutri;</code> or <code>&oplus;</code>) of the provided arrays. In other words, start with the first array and keep on taking symmetric differences of each the following arrays after it.",
         "Given two sets (for example set <code>A = {1, 2, 3}</code> and set <code>B = {2, 3, 4}</code>), the mathematical term \"symmetric difference\" of two sets is the set of elements which are in either of the two sets, but not in both (<code>A &xutri; B = C = {1, 4}</code>). For every additional symmetric difference you take (say on a set <code>D = {2, 3}</code>), you should get the set with elements which are in either of the two the sets but not both (<code>C &xutri; D = {1, 4} &xutri; {2, 3} = {1, 2, 3, 4}</code>). The resulting array must contain only unique values (<em>no duplicates</em>).",
         "Remember to use <a href='http://forum.freecodecamp.com/t/how-to-get-help-when-you-are-stuck/19514' target='_blank'>Read-Search-Ask</a> if you get stuck. Try to pair program. Write your own code."
       ],