add information about sudo class

README.md

@@ -29,3 +29,20 @@ chroot environments for Debian `sid`, `stretch`, `jessie`, and Ubuntu
     }
 
 The above also installs a daily cron job to update the chroots.
+
+## Using sudo
+
+In order to run `pbuilder` as a non-root user you need to add the
+following line to `/etc/sudoers`:
+
+    %root    ALL = NOPASSWD: /usr/sbin/cowbuilder
+
+The `su_debuild` module provides a convenience class to do this,
+`su_debuild::sudo`. Here is how you can install all the packages, chroots,
+and set up sudo:
+
+    include su_debuild
+    include su_debuild::sudo
+    class { 'su_debuild::chroots':
+      chroots => [ 'sid', 'stretch', 'jessie', 'bionic']
+    }