Security: Add documentation and guidance for the EC2 client's egress 443 rule

[ckamps]

And add inline comments around the egress rule for 443 to explain the purposes for the egress rule (AWS package downloads, connectivity to AWS Systems Manager and other AWS services - be specific). Also highlight that in a more formal implementation, the CIDR should be changed from 0.0.0.0/0 to be more specific and align with how connectivity to such endpoints is established.