Our refdocs have an SSL page: [https://mongodb.github.io/mongo-csharp-driver/2.10/reference/driver/ssl/
]
We should replace all references to SSL with TLS/SSL, and update the URI options provided to use the TLS variants.

We can model some of the changes after the java refdocs page: https://mongodb.github.io/mongo-java-driver/4.0/driver/tutorials/ssl/