Support Matrix table for supported operators on ppc64le requires update

Description of problem:

There is a section under https://docs.openshift.com/container-platform/4.15/release_notes/ocp-4-15-release-notes.html#ocp-4-15-ibm-power called "IBM Power, IBM Z, and IBM LinuxONE support matrix".  Table 3. consists of supported operators.

There are 2 changes for Power that need to be made for 4.15 release:

1. Network Observability operator should to be added.
2. Service Binding Operator should be removed.

Justification:

Network Observability operator is supported on ppc64le since version 1.3.0 - https://docs.openshift.com/container-platform/4.15/network_observability/network-observability-operator-release-notes.html#network-observability-operator-release-notes-1-3

Service Binding Operator is supported on OCP till version 4.12 - https://docs.openshift.com/container-platform/4.15/applications/connecting_applications_to_services/sbo-release-notes.html