Update README

[punchagan]

• Improve description of the repository
• Add basic installation and development environment setup instructions
• Add instructions to deploy new changes to Heroku
• May be add contribution guidelines or link to some existing guidelines

[vkrishnaswam]

@punchagan can you please update the last two. I'm sure I'm not capturing all the details in what I have updated now.

[punchagan]

I've merged the existing commit, since that looks good for now. We can add more updates, if and when we see the need for it. I was particularly keen on having the description changed, and so merged your first-cut PR. Thanks for working on this!