Update AWS install docs for non HA

doc/install/aws/index.md

-# Installing GitLab on Amazon Web Services (AWS)
-
-To install GitLab on AWS, you can use the Amazon Machine Images (AMIs) that GitLab
-provides with [each release](https://about.gitlab.com/releases/).
+# Installing GitLab HA on Amazon Web Services (AWS)
 This page offers a walkthrough of a common HA (Highly Available) configuration
 for GitLab on AWS. You should customize it to accommodate your needs.
+NOTE: **Note**
+For organizations with 300 users or less, the recommended AWS installation method is to launch an EC2 single box [Omnibus Installation](https://about.gitlab.com/install/) and implement a snapshot strategy for backing up the data.
+
 ## Introduction
 GitLab on AWS can leverage many of the services that are already