Docs: Missing requirements for AWS creds when publishing AMI

[jpmcb]

Platform I'm building on:

OS: Fedora 34 (Cloud Edition) aarch64
Host: c6g.8xlarge
Kernel: 5.11.12-300.fc34.aarch64
Cargo: cargo 1.62.1 (a748cf5a3 2022-06-08)

What I expected to happen:

According to the BUILDING.md quickstart docs, the following should produce an AMI and print out it's ID:

❯ cargo make -e PUBLISH_REGIONS=us-east-2 ami

What actually happened:

Instead, it errors out on missing credentials:

[cargo-make] INFO - cargo make 0.35.16
[cargo-make] INFO - Build File: Makefile.toml
[cargo-make] INFO - Task: ami
[cargo-make] INFO - Profile: development
[cargo-make] INFO - Running Task: setup
[cargo-make] INFO - Running Task: setup-build
[cargo-make] INFO - Running Task: fetch-sources
[cargo-make] INFO - Running Task: publish-tools
[cargo-make] INFO - Running Task: ami
/home/fedora/workspa : decoded 2147483648 bytes
/home/fedora/workspa : decoded 1073741824 bytes
Failed to build AMI: Error getting AMI ID for arm64 bottlerocket-aws-k8s-1.21-aarch64-v1.10.0-2a6c5e92 in us-east-2: Failed to describe images in us-east-2: Couldn't find AWS credentials in environment, credentials file, or IAM role.
[cargo-make] ERROR - Error while executing command, exit code: 1
[cargo-make] WARN - Build Failed.

This makes sense since my new devbox doesn't have the aws CLI or my creds in it yet. But, neither the BUILDING.md nor the PUBLISHING.md doc make reference to the aws CLI or the requirement to load creds for your AWS account.

How to reproduce the problem:

On a new devbox with no AWS, follow the BUILDING.md to build and register a new AMI.