This commit enhances the docs about IAM encryption.
It adds a quick-start section that explains how to
get started quickly with `MINIO_KMS_SECRET_KEY`
instead of setting up KES.
It also removes the startup message that gets printed
when the server migrates IAM data to plaintext.
We will point this out in the release notes.
Signed-off-by: Andreas Auernhammer <aead@mail.de>
Bonus fix fallback to decrypt previously
encrypted content as well using older master
key ciphertext format.
Signed-off-by: Harshavardhana <harsha@minio.io>
