Need to call out 'platform' field in spec on EKS page

If you deploy a Couchbase Server cluster using the operator on AWS with public DNS without specifying the 'platform' field as 'aws', then the load balancers will not correctly deploy, meaning that applications cannot access the Database.

While this field is listed under the Couchbase configuration, this is hidden away and requires a lot of scrolling.
We need to call this requirement out specifically on https://docs-staging.couchbase.com/operator/1.2/install-eks.html.