Inconsistent aws configure behavior involving Windows environment variable

[tim-finnigan]

Describe the bug

In the SDKs & Tools Reference Guide, it mentions that all platforms first check the HOME environment variable for the config and credentials files.

But in the CLI configuration documentation it notes:

The AWS CLI stores sensitive credential information that you specify with aws configure in a local file named credentials, in a folder named .aws in your home directory. The less sensitive configuration options that you specify with aws configure are stored in a local file named config, also stored in the .aws folder in your home directory.

Where you find your home directory location varies based on the operating system, but is referred to using the environment variables %UserProfile% in Windows and $HOME or ~ (tilde) in Unix-based systems.

We need to confirm:

• If all SDKs first look for the HOME environment variable in Windows environments.
• If aws configure should be updated to update the HOME environment variable in Windows.
• If SDK/CLI documentation should be updated to clarify this behavior.

Originally reported here: #7035

Related Go PR: aws/aws-sdk-go#1308