[docs][xs]: fix instructions to install dependencies from the requriements.txt + add python version badge.

README.md

@@ -47,10 +47,12 @@ We will endeavour to provide more detail on how regularly and by which technical
 
 ## Preparation
 
-This repository uses [dataflows](https://github.com/datahq/dataflows) to process and normalize the data:
+This repository uses [dataflows](https://github.com/datahq/dataflows) to process and normalize the data.
+
+You first need to install the dependencies:
 
 ```
-pip install dataflows
+pip install -r requirements.txt
 ```
 
 Then run the script
@@ -59,6 +61,7 @@ Then run the script
 python process.py
 ```
 
+[![Python 3.6](https://img.shields.io/badge/python-3.6-blue.svg)](https://www.python.org/downloads/release/python-360/)
 ![.github/workflows/actions.yml](https://github.com/datasets/covid-19/workflows/.github/workflows/actions.yml/badge.svg?branch=master)
 
 ## License