Specify TLS configuration is per-node

[ravindk89]

Summary

There's some user confusion on configuring TLS for distributed MinIO.

• https://docs.min.io/minio/baremetal/security/network-encryption/minio-tls.html
• https://docs.min.io/minio/baremetal/installation/deploy-minio-distributed.html#add-tls-ssl-certificates
• https://docs.min.io/minio/baremetal/installation/expand-minio-distributed.html#add-tls-ssl-certificates

Users might read this as configuring some sort of cluster/replicated configuration.

We should specify that users must:

• Configure TLS per node
• The TLS certificate SAN must apply to the hostname for it's parent node (e.g. if non-wildcard SAN)
• The CAs directory must contain the appropriate CA if the certificates are self-signed or internally signed
• Update the URLs to be https:// after the fact

Worth also noting that MinIO may not automatically create the directory .minio/certs or .minio/certs/CAs - need to test this on RHEL8 and Ubuntu LTS.

Goals

List the in-scope goals

• Update TLS configuration docs to specify per-node
• Create a simple checklist for TLS certs (permissions, SAN, and path)
• Update TLS config docs to call out updating endpoints from HTTP -> HTTPS

Non-Goals

Actual tutorials on using openssl or certbot to generate self-signed certs

Additional context
Add any other context or screenshots about the feature request here.