Update introduction.md (exercism#2514)

I think the introduction for this exercise was missing crucial information that prevented a learner from completing the task without doing external research. I've added additional information that should be sufficient to allow the learner to complete the task without any additional Googling.

Author: JorensM

Diff for: exercises/concept/ozans-playlist/.docs/introduction.md

@@ -25,5 +25,31 @@ console.log(set.size);
 //=> 4
 ```
 
+You can provide an array as an argument when creating a set, and the array's values will become the values of the set, also removing the duplicate values.
+
+```javascript
+const array = [1, 5, 4, 1];
+const set = new Set(array); // the set's values become [1, 5, 4]
+
+console.log(set.size);
+//=> 3
+```
+
+To convert a set to an array, you can use [Array.from()][mdn-array-from], which converts an iterable such as a set or a map to an array.
+
+```javascript
+const set = new Set();
+
+set.add(1);
+set.add(2);
+set.add(3);
+set.add(4);
+
+const array = Array.from(set);
+console.log(array);
+//=> [1, 2, 3, 4]
+```
+
 [mdn-sets]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Set
 [mdn-strict-equality]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Equality_comparisons_and_sameness#strict_equality_using
+[mdn-array-from]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/from