Improve docs for `cockroach connect` / Auto TLS

[exalate-issue-sync[bot]]

Michael Lewis (mikeCRL) commented:

The Auto TLS capability centers around the {{cockroach connect}} command.

We have [documented Auto TLS](https://www.cockroachlabs.com/docs/stable/auto-tls.html] here, but there is no entry for cockroach connect in the nav. This should be added. It could link directly to the Auto TLS docs if there’s any precedent for linking to a page that’s not explicitly about the command itself; otherwise, we can create a short page about the command and rely heavily on links out to the Auto TLS page.

Per [~accountid:6050cd7e009fee006928904e), the Auto TLS page needs improvement; specifically, that it should include examples of using cockroach connect join and using a token.

This matter was first raised in this thread. This issue is a higher priority update than the additional work recommended in https://cockroachlabs.atlassian.net/browse/DOC-2379.

Jira Issue: DOC-2378