Fixed Broke Link aws.discovery.ec2-download-user-data.md

[austinsonger]

What does this PR do?

Fixed Broken Link

Motivation

Checklist

• The attack technique emulates a single attack step, not a full attack chain
• We have factual evidence & references that the attack technique was used by real malware, pentesters, or attackers
• The attack technique makes no assumption about the state of the environment prior to warming it up

[christophetd]

Thanks!