extend finding AMI documentation to give links to limit accounts which amis can be used

a new feature was introduced at RIV that can allow users to limit which account number can be used to limit which accounts AMIs can be listed on your account. we should extend our documentation to point to this documentation.

https://aws.amazon.com/about-aws/whats-new/2024/12/amazon-ec2-allowed-amis-enhance-ami-governance/

Search the documentation for the existing section about finding or listing AMIs and start by reading its surrounding guidance. Add a link to the AWS documentation on allowed AMIs and verify that the page clearly points readers to the account-limiting feature.

Written by the indexing model from the issue text.