How do I export my SAIL code to my GIT repository?

Appian has provided a Deployment Automation for your above requirement. Please check the below link.
forum.appian.com/.../Deployment_Automation.html

I would like to mention a point which might be a bottleneck and i.e. Exporting the Appian to GIT part.
Currently there is no way to export an application from Command Line.
If you wish to automate the full procedure then you might have to do some customizations in order to export the application from appian. Or else you can always export the application manually and then place it in your desired location and then the Deployment Automation can takeover.

There is no way to create the ZIP automatically. It has to be a manual procedure?
Thanks sidhant, your response has been helpful.

@ishaanim - Hope Appian provides Command Line Interface for Exporting application like Import Manager. Anyways, Happy to Help :-)