Added Contribution Guide

Author: ashokdey

README.md

@@ -60,3 +60,23 @@ Collection of interview questions with Unit Tests. Problems includes Data Struct
 
 - [Caeser Cipher](src/_Classics_/caeser_cipher)
 - [Fibonacci](src/_Classics_/fibonacci)
+
+---
+
+## CONTRIBUTION Guide
+
+It's great to know that you want to contribute to this repo. Thanks for taking interest. Before you start, read the following carefully. 
+
+- When adding a new **problem** with solution
+  - Take care of the filename convention (Very Important)
+  - Problem statement should be there with examples
+  - Make sure you add the Run Time complexity of your solution
+  - Please take care of the segregation of the Problems as per the given Folder Structure
+  - It's great if you can add the **Unit Tests** to verify your solutions as well
+  - Strictly follow ESLINT rules
+
+- When adding a Unit Test
+  - Take care of the file name convention
+  - Make sure CI (Travis) is passing
+  
+Keep an eye on this guide, it's subjected to change frequently.