Update CountSinglyLinkedListRecursion.java (TheAlgorithms#2170)

Only method comment for public recursive method.

Author: DennisVNilsson

DataStructures/Lists/CountSinglyLinkedListRecursion.java

@@ -18,7 +18,9 @@ public static void main(String[] args) {
   private int countRecursion(Node head) {
     return head == null ? 0 : 1 + countRecursion(head.next);
   }
-
+  /**
+  *Returns the count of the list.
+  */
   @Override
   public int count() {
     return countRecursion(getHead());