add bash options

`-e`: exits upon encountering any error, usually with rc 1
`-u`: exits upon encountering any unset variables; not applicable here, but a good practise nonetheless
`-o pipefail`: enables the `pipefail` option which terminates a pipeline upon encountering an error in any of its steps
`-x`: repeats shell commands as they are executed, i.e. "shell tracing"

Author: carlosonunez-vmw

Diff for: examples/docker-rootful.yaml

@@ -59,6 +59,7 @@ provision:
     #!/bin/bash
     # Increase inotify limits to prevent nested Kubernetes control planes
     # from crash looping.
+    set -eux -o pipefail
     echo 'fs.inotify.max_user_watches = 524288' >> /etc/sysctl.conf
     echo 'fs.inotify.max_user_instances = 512' >> /etc/sysctl.conf
     sysctl --system