correct function scaling doc

Signed-off-by: wrongerror <wangyifei@kubesphere.io>

Author: wrongerror

content/en/docs/concepts/function_scaling_trigger.md

@@ -69,15 +69,14 @@ spec:
   serving:
     scaleOptions:
       knative:
-        autoscaling:
-          autoscaling.knative.dev/min-scale: 0
-          autoscaling.knative.dev/max-scale: 10
-          autoscaling.knative.dev/initial-scale: "1"
-          autoscaling.knative.dev/scale-down-delay: "0"
-          autoscaling.knative.dev/window: "60s"
-          autoscaling.knative.dev/panic-window-percentage: "10.0"
-          autoscaling.knative.dev/metric: "concurrency"
-          autoscaling.knative.dev/target: 100
+        autoscaling.knative.dev/min-scale: "0"
+        autoscaling.knative.dev/max-scale: "10"
+        autoscaling.knative.dev/initial-scale: "1"
+        autoscaling.knative.dev/scale-down-delay: "0"
+        autoscaling.knative.dev/window: "60s"
+        autoscaling.knative.dev/panic-window-percentage: "10.0"
+        autoscaling.knative.dev/metric: "concurrency"
+        autoscaling.knative.dev/target: "100"
 ```
 
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