Update vespa-http-client example to use SSL

[frodelu]

Since we should expect SSL to be the default going forward, we should update our example in the vespa-http-client documentation to use SSL.

We should also add --useTls in the command line example.

[jobergum]

Care must be taken here as in some envs you might feed through a proxy layer with ssl termination and in other envs you might feed directly against vespa containers and in the latter case the vespa containers needs to be configured with SSL and certificates.

[kkraune]

I think we can close this with the new https://docs.vespa.ai/en/vespa-feed-client.html , right @jonmv ?

[jonmv]

Sort of. So this requires each container to set up TLS, and terminating at a proxy is not an option (unless the proxy again uses TLS against the containers).

[johans1]

use new client

[kkraune]

docs and sample apps are being rewritten to use vespa-feed-client, no need to change for vespa-http-client - closing