Update README with the new call_for_membership_fees command

README.md

@@ -120,6 +120,11 @@ membership fee, his or her address will still show up in this list.
 PDF version) for each subscriber.  You probably want to run this command
 every month as a cron task, see below.
 
+`python manage.py call_for_membership_fees`: send reminder emails to members
+whose membership fee is about to expire or is already expired (1 month before,
+on the day of expiration, 1 month after, 2 months after, and 3 months after).
+You should run this command in a cron job every day.
+
 
 Configuration
 =============
@@ -150,6 +155,10 @@ To generate invoices on the first day of each month, here at 3 am:
 
 `0 3 1 * * /home/coin/venv/bin/python manage.py charge_subscriptions`
 
+To send reminder emails for membership fee expiration:
+
+`42 3 * * * /home/coin/venv/bin/python manage.py call_for_membership_fees`
+
 
 More information
 ================