Changes to override json and docs to support OCP 4.15

[ocofaigh]

Whenever the MAS DA supports 4.15, your going to want to make the following changes:

• update the override.json to include "disable_outbound_traffic_protection": true since you will need outbound traffic to pull your docker images. This is required because in OCP 4.15, outbound traffic is disabled by default
• Also update the version in the override json to "kube_version": "4.15_openshift"
• Update your cloud docs to make it clear that outbound traffic is required to be opened in the cluster that MAS is deploying to