Fix container registry MinIO configuration example

What does this MR do?

Found this while helping to debug an issue reported by a customer (internal).

There are multiple things wrong in the current example:

1. aws_signature_version is not a valid configuration parameter. The correct one is v4auth, which is a boolean and defaults to true;
2. provider and host are not known and therefore ignored;
3. There is no path_style configuration, the correct name is pathstyle, which is a boolean.

I suspect this example was copied from a Rails object storage configuration example, but it doesn't apply to the registry.

Checklist

See Definition of done.

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