server.org add instructions for resetting user passwords

doc/server.org

@@ -325,3 +325,10 @@ These installation instruction are for Ubuntu server 14.04
   - Run unit tests (Simply a precaution: Continuous Integration renders this
     step redundant but it's better to be sure)
   - Check site functionnality
+
+* Resetting user passwords
+  Currently there is not easy way of resetting a user's password.
+  The current method is the following:
+  `cd server/web2py`
+  `python web2py -S vidjil -M`
+  `db.auth_user[<user-id].update_record(password=CRYPT(key=auth.settings.hmac_key)('<password>')[0],reset_password_key='')`