Add Akri and connectors to TOC

Author: vadim-kovalyov

articles/iot-operations/toc.yml

@@ -396,6 +396,9 @@ items:
               - name: Connector for OPC UA
                 href: reference/observability-metrics-opcua-broker.md
                 displayName: metrics, observability
+              - name: Akri and connectors
+                href: reference/observability-metrics-akri-connectors.md
+                displayName: metrics, observability
               - name: Layered Network Management
                 href: reference/observability-metrics-layered-network.md
                 displayName: metrics, observability