Add Rush change file for managedByExtended feature

Co-authored-by: mikeharder <9459391+mikeharder@users.noreply.github.com>

Author: Copilot

common/changes/@microsoft.azure/openapi-validator-rulesets/copilot-add-managedByExtended_2026-01-29-06-01.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@microsoft.azure/openapi-validator-rulesets",
+      "comment": "Add managedByExtended to allowed body top-level properties",
+      "type": "patch"
+    }
+  ],
+  "packageName": "@microsoft.azure/openapi-validator-rulesets"
+}