Merge pull request kubernetes#37785 from tanshanshan/fix-small

Automatic merge from submit-queue (batch tested with PRs 37692, 37785, 37647, 37941, 37856)

fix scheduler extender example

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**What this PR does / why we need it**:

Fix scheduler extender example , refer to [kubernetes/plugin/pkg/scheduler/api/types.go](https://github.com/kubernetes/kubernetes/blob/master/plugin/pkg/scheduler/api/types.go)

Thanks!
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Author: Kubernetes Submit Queue

examples/scheduler-policy-config-with-extender.json

@@ -14,12 +14,14 @@
 	{"name" : "ServiceSpreadingPriority", "weight" : 1},
 	{"name" : "EqualPriority", "weight" : 1}
 	],
-"extender": {
-        "url": "http://127.0.0.1:12346/scheduler",
+"extenders":[ 
+	{
+        "urlPrefix": "http://127.0.0.1:12346/scheduler",
         "apiVersion": "v1beta1",
         "filterVerb": "filter",
         "prioritizeVerb": "prioritize",
         "weight": 5,
         "enableHttps": false
-    }
+	}
+    ]
 }