hubble/observer/types: fix comment for AgentEvent.Message
hubble/observer/types: fix comment for AgentEvent.Message

It might contain a monitorAPI.AgentNotifyMessage as emitted by the
*Message constructor funcs.

Signed-off-by: Tobias Klauser <9249c549618448e4c699e8032ba6c7f0d7fd4b7f@distanz.ch>

tklauser/cilium,tgraf/cilium,tgraf/cilium,cilium/cilium,cilium/cilium,cilium/cilium,michi-covalent/cilium,tgraf/cilium,michi-covalent/cilium,tklauser/cilium,cilium/cilium,tgraf/cilium,michi-covalent/cilium,tklauser/cilium,michi-covalent/cilium,tgraf/cilium,cilium/cilium,michi-covalent/cilium,tgraf/cilium,tklauser/cilium,tklauser/cilium