Merge branch 'choffner/elasticsearch_ec2_clarification' into 'master'

Docs: Specify what an EC2 instance means

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/183910



Merged-by: Amy Qualls <aqualls@gitlab.com>
Approved-by: Amy Qualls <aqualls@gitlab.com>
Co-authored-by: Ciaran Hoffner <choffner@gitlab.com>