Updated README.md

[saurabhhere]

Related to:

Resolves: #54

Description:

Added link to CONTRIBUTING.md in README.md

Checklist:

Please put an x in each box that you have completed

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my own code
• [x] I have commented my code in any hard-to-understand areas
• [x] My changes generate no new warnings or errors

[saurabhhere]

@capndave Have a look at it.

[capndave]

Looks great, thanks!