Cloud Connection sample code update

Quoth AV: "As per the discussion in SDK meeting held on July 14th, it was deemed necessary that the SDK code samples for Cloud would be a bit outdated / behind."

& qoth RS:  "Please review the connection sample for Cloud on the Hello World page,
for changes in API, or any oddities,
and comment out the sslverify = false (so that we can suggest when it is appropriate,
and add in the relevant TLS certificate code
(we will add in downloading the Cloud Cert to the doc.
Thanks."

Note, this is the sample that appears in the Cloud tab at https://docs.couchbase.com/dotnet-sdk/current/hello-world/start-using-sdk.html#full-example

and lives at https://github.com/couchbase/docs-sdk-dotnet/blob/d6d16cd570984866e3d0af5e798cb3842ad3e4c1/modules/devguide/examples/dotnet/Cloud.cs