CRW 2.4 docs for s390x

Overall tracker for Z-specific doc issues.

• platform requirements (OCP versions that are supported, eg., OCP 3.11 is NOT supported, and the specific 4.x versions may differ by arch)

• images that will be installed (see airgap/restricted environment instructions and lists of images – for Z & P we intend to have OpenJ9 versions of SSO, EAP, and the plugin-java* images)

• supported devfiles (dotnet doesn't exist on Z & P)

• install methods (currently crwctl is NOT supported for Z or P since the expectation is that uses will use OperatorHub UI inside the cluster, or else do stuff by hand with oc commands)

• known issues may include some Z or P specific issues / caveats / workarounds