Add a graph to display doubling rate

Created by: kracekumar

Is your feature request related to a problem? Please describe.

Now that cases are doubling quicker, it may be better to have a doubling rate at country level and state-level as a time-series. Y-axis "no of days" and x-axis "number of cases".

Describe the solution you'd like This is a step to find out the "flatten the curve" is happening or not. Example: https://covid19-india.datameet.org//dashboard/

By this one can say, how each state is performing, who is lacking, and who are doing well