Fix aws secret key name in autoscaler aws target

- aws secret key is named incorrectly in the target docs.
  It needs to match what is in the nomad-autoscaler repo
  (see link below), otherwise the autoscaler will default to AWS sdk
  behavior, which could end up using an IAM instance profile
  or other environment variables instead of what is passed into the
  autoscaler config file.

Ref: https://github.com/hashicorp/nomad-autoscaler/blob/e60fb5268d2107ab18e2be11e5d438fedc3eb2a8/plugins/builtin/target/aws-asg/plugin/plugin.go#L27

website/content/docs/autoscaling/plugins/target.mdx

@@ -169,9 +169,9 @@ below.
 target "aws-asg" {
   driver = "aws-asg"
   config = {
-    aws_region        = "eu-west-3"
-    aws_access_key_id = "AKIAIOSFODNN7EXAMPLE"
-    aws_secret_key_id = "wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY"
+    aws_region            = "eu-west-3"
+    aws_access_key_id     = "AKIAIOSFODNN7EXAMPLE"
+    aws_secret_access_key = "wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY"
   }
 }
 ```
@@ -191,7 +191,7 @@ node {
 - `aws_access_key_id` `(string: "")` - The AWS access key ID used to authenticate
   with the AWS API.
 
-- `aws_secret_key_id` `(string: "")` - The AWS secret key ID used to authenticate
+- `aws_secret_access_key` `(string: "")` - The AWS secret key ID used to authenticate
   with the AWS API.
 
 - `aws_session_token` `(string: "")` - The AWS session token used to authenticate