Existing doc page (covers only operator upgrade - via inplace/canary): https://docs.redhat.com/en/documentation/red_hat_openshift_service_mesh/3.0/html/updating/ossm-updating-openshift-service-mesh#ossm-updating-openshift-service-mesh.

Drafted complete documentation (covers full upgrade path with explanations): https://github.com/openshift-service-mesh/sail-operator/tree/main/docs/ossm/versioning-and-upgrades

Old description:

This exists already, but only covers updating the Istio control plane (which is only part of the procedure): https://docs.openshift.com/service-mesh/latest/update/ossm-updating-openshift-service-mesh.html

• Understanding versioning (content for this and the next two sections is drafted here)
• Understanding Service Mesh & Istio versions (We only support the latest Istio release)
• Operator Updates & Channels (Note: No update procedure for the operator if they selected 'automatic', but we still need to explain it)

Note: Existing content should be reviewed against the upstream content as well, as it may have changed.