#206: description update

Author: vetalapo

c-sharp/Problems/linked-list/ReverseLinkedList.cs

@@ -4,7 +4,25 @@
  **
  * Given the head of a singly linked list, reverse the list, and return the reversed list.
  *
- * Follow up: A linked list can be reversed either iteratively or recursively. Could you implement both?
+ * Example 1:
+ *   Input: head = [1,2,3,4,5]
+ *   Output: [5,4,3,2,1]
+ *
+ * Example 2:
+ *   Input: head = [1,2]
+ *   Output: [2,1]
+ *
+ * Example 3:
+ *   Input: head = []
+ *   Output: []
+ *
+ * Constraints:
+ *   • The number of nodes in the list is the range [0, 5000].
+ *   • -5000 <= Node.val <= 5000
+ *
+ * Follow up:
+ *   A linked list can be reversed either iteratively or recursively.
+ *   Could you implement both?
  **
  * https://leetcode.com/problems/reverse-linked-list/
 ***/