Enabling others to comment on your posts is a nice to have feature for a blog. Disqus is an online tool which can be used to do this. It is pretty easy to integrate with your Jekyll Site.
Create an Account on Disqus
This is pretty easy so I am not going to explain this.
Create a new Site
When you have logged into your account you will be able to create a site.
Embed the code
First you need to add a variable to the YAML Formatter. I added this to all my posts.
Then emded the JavaScript to the template.
My Disqus Configuration looks like this
Now you should be able to see a comments section for each post.