Add additional guidance and considerations around utilizing EKS Auto Mode

**Describe the best practice**
A new EKS Auto Mode section specific to auto-scaling has been added to the best practices guide. However, there are other considerations and best practices around Auto Mode that are worthwhile to communicate. For instance: When add managed node groups to an Auto Mode cluster the user must also deploy the add ons for VPC CNI, Core DNS, and Kube Proxy. It probably makes sense to have a top level Auto Mode page with recommendations like this that can link off to pages like the autoscaling overview.

Review the existing EKS best practices guide, especially the new Auto Mode auto-scaling section and the autoscaling overview it references. Add a top-level Auto Mode page covering the stated managed node group and add-on considerations, with links to related guidance; done means the recommendations are clear and cross-linked.

Written by the indexing model from the issue text.