Palindrome Linked List

Hello I'm a participant of Hacktoberfest 2021. I'm very new to open source. I want to contribute in your repo DSA-Linked List by adding this problem with a solution in C++. Please assign me this issue.

**Problem Statement :**
You have been given a head to a singly linked list of integers. Write a function check to whether the list given is a 'Palindrome' or not.

**Consider:**
While specifying the list elements for input, -1 indicates the end of the singly linked list and hence, would never be a list element.

**Sample Input 1:**
9 2 3 3 2 9 -1

**Sample Output 1:**
true

**Sample Input 2:**
0 2 3 2 5 -1

**Sample Output 2:**
false