S3A third party: document "Certificate doesn't match"

A recurrent problems with third party stores is that the user gets an error message about HTTP certificates

Unable to execute HTTP request: Certificate for <mybucket.mystore.dev.net> doesn't match any of the subject alternative names: [*.dev.net]

This is happening because

1. the store uses HTTPS and there is an organization certificate
2. the store does support virtual hostname access -but it does not match the HTTPS wildcard

Fix: switch to path style access

add this detail to the third party store doc