Add Zigbee R23 add-on v1.2.0

Add new version of Zigbee R23 add-on - v1.2.0.

Signed-off-by: Eduardo Montoya <eduardo.montoya@nordicsemi.no>

Author: edmont

index/nrfconnect.json

@@ -112,6 +112,12 @@
           "tag": "v1.1.0",
           "date": "2025-08-08T12:32:00Z",
           "sdk": "v2.9.0"
+        },
+        {
+          "name": "Zigbee add-on v1.2.0",
+          "tag": "v1.2.0",
+          "date": "2025-08-22T13:21:00Z",
+          "sdk": "v2.9.0"
         }
       ],
       "defaultBranch": "v1.1.0",