Upload .csv with R estimates to the webpage

[hazarane]

Description

Currently the R estimates are exported to .csv, however it's not uploaded anywhere. We need to upload it to the web page and link it in /country-rt-estimates page.

Acceptance Criteria

-On the /country-rt-estimates page under the plot display one more sentence at the beginning "The displayed time-series can be downloaded in .csv format [here](link to the file with R estimates). The time-series show our estimate of the effective reproduction number...... "
-The .csv file should be updated daily, the same as we update the R values for the plot.