IAM Joining Docs: Set join_method in token.yaml (#10433)

docs/pages/setup/guides/joining-nodes-aws.mdx

@@ -123,6 +123,9 @@ spec:
   # use the minimal set of roles required
   roles: [Node]
 
+  # set the join method allowed for this token
+  join_method: iam
+
   allow:
   # specify the AWS account which nodes may join from
   - aws_account: "111111111111"
@@ -167,6 +170,9 @@ spec:
   # use the minimal set of roles required
   roles: [Node]
 
+  # set the join method allowed for this token
+  join_method: ec2
+
   # aws_iid_ttl is the amount of time after the EC2 instance is launched during
   # which it should be allowed to join the cluster. Use a short TTL to decrease
   # the risk of stolen EC2 Instance Identity Documents being used to join your