update iam policy version to 2.4.7 (kubernetes-sigs#3123)

Author: oliviassss

docs/deploy/installation.md

@@ -81,15 +81,15 @@ Example condition for cluster name resource tag:
 2. Download an IAM policy for the LBC using one of the following commands:<p>
     If your cluster is in a US Gov Cloud region:
     ```
-    curl -o iam-policy.json https://raw.githubusercontent.com/kubernetes-sigs/aws-load-balancer-controller/v2.4.6/docs/install/iam_policy_us-gov.json
+    curl -o iam-policy.json https://raw.githubusercontent.com/kubernetes-sigs/aws-load-balancer-controller/v2.4.7/docs/install/iam_policy_us-gov.json
     ```
     If your cluster is in a China region:
     ```
-    curl -o iam-policy.json https://raw.githubusercontent.com/kubernetes-sigs/aws-load-balancer-controller/v2.4.6/docs/install/iam_policy_cn.json 
+    curl -o iam-policy.json https://raw.githubusercontent.com/kubernetes-sigs/aws-load-balancer-controller/v2.4.7/docs/install/iam_policy_cn.json
     ```
     If your cluster is in any other region:
     ```
-    curl -o iam-policy.json https://raw.githubusercontent.com/kubernetes-sigs/aws-load-balancer-controller/v2.4.6/docs/install/iam_policy.json  
+    curl -o iam-policy.json https://raw.githubusercontent.com/kubernetes-sigs/aws-load-balancer-controller/v2.4.7/docs/install/iam_policy.json
     ```
 
 3. Create an IAM policy named `AWSLoadBalancerControllerIAMPolicy`. If you downloaded a different policy, replace `iam-policy` with the name of the policy that you downloaded.