Create realtime_analytics.md

Realtime analytics allows you to drive solid business decisions with precise analytics on your transactional and 
marketing email campaigns. Easily categorize separate email campaigns and track statistics down to the email address. 
Data is real-time and available via our intuitive [web based dashboard](https://sendgrid.com/docs/Marketing_Emails/dashboard.html)
or customizable through our [Event Notification app] (https://sendgrid.com/docs/Apps/event_notification.html) 
and/or [Web APIs] (https://sendgrid.com/docs/API_Reference/Web_API/index.html).