Add High Availability Section to NeuVector Architecture Document

Add a High Availability section to the NeuVector architecture document. These sections for other packages can be used as examples:

• https://repo1.dso.mil/platform-one/big-bang/bigbang/-/blob/master/docs/understanding-bigbang/package-architecture/authservice.md#high-availability
• https://repo1.dso.mil/platform-one/big-bang/bigbang/-/blob/master/docs/understanding-bigbang/package-architecture/kiali.md#high-availability

It looks like every pod within the NeuVector chart is able to run with multiple replicas out of the box besides the manager pod (which appears to be the UI). The chart is set for multiple replicas by default for all pods except manager. Document this case and ensure YAML examples of multiple replicas are present with the architecture document along with any explicit requirements for running in HA (external DB, no PVCs, etc.)

AC:

• High Availablity section added to NeuVector architecture document