Add documentation on how to fix bad bootstrap.

Add documentation on how to fix bad bootstrap.

README.md

@@ -283,6 +283,22 @@ https://registry2.comanage.incommon.training
 
 for node 2, and so on.
 
+## Fixing a bad bootstrap
+
+Trainees that do not follow the instructions closely may bootstrap
+COmanage Registry with a configuration that does not allow them
+to authenticate as the platform administrator. When that happens
+follow these steps on the training node as the root user:
+
+1. `docker stack rm comanage`
+1. `cd /srv/docker/var/lib/mysql`
+1. `rm -rf ./`
+1. `cd /srv/docker/srv/comanage-registry/local/Config`
+1. `rm -rf ./`
+
+Then tell the user to correct the error in the stack file
+and try again.
+
 ## Interference from existing SSH agent
 
 If you find that your existing SSH agent is interfering with the SSH connections