Update setup steps for Ratify killercoda

[susanshi]

Steps at https://killercoda.com/notaryproject/scenario/ratify needs to be updated.
Looks like the install command is out of date, i believe we renamed notaryCert to notationCerts: [].
helm install ratify
./charts/ratify --atomic
--namespace gatekeeper-system
--set-file notaryCert=./notary.crt

[FeynmanZhou]

This online environment is outdated and needs refresh. @kokamkarsahil is the contributor of this interactive environment and the source code is under this repo https://github.com/killercoda-examples/notary-scenerios/tree/main/ratify.

@kokamkarsahil Do you still have any bandwidth to help update it?

[FeynmanZhou]

The Ratify version needs to be update to v1.2.0 either.