- weed-shell.md: replace s3.configure and s3.bucket.access in command
listing with new commands (s3.user.*, s3.accesskey.*, s3.anonymous.*,
s3.serviceaccount.*, s3.policy.attach|detach, s3.iam.*, s3.config.show,
s3.user.provision). Add "S3 IAM Management" section with workflow examples.
- S3-Credentials.md: update shell examples to use new commands instead
of s3.configure.
- S3-Configuration.md: add shell command examples to Embedded IAM section.
- _Sidebar.md: add weed shell link under S3 Authentication & IAM.