Add availability of using API keys to connect to Temporal Cloud in language SDK pages

[cdavisafc]

Temporal Affiliation

• [x] I am a Temporal employee

Page URL

https://docs.temporal.io/develop/go/core-application#run-a-temporal-cloud-worker

Content Issue

At least the Go SDK page, and perhaps other languages, only mentions using certs to connect to Temporal Cloud, when API keys are also now supported.

List API keys as another option, linking to the docs page that describes the details.