Add README to samples

[alexortizrosado]

The samples needs a README with steps on how to

1. download the code (git clone)
2. install requirements (pip install)
3. run the easytithe_importer.py script

Basically, all the same steps done by the cron job: https://github.com/rohichurch/rohichurch-wp/blob/master/cron/easytithe_import.sh