[Feature Request] More information in "request not authenticated" error

[ktdilsiz]

Is your feature request related to a problem? Please describe.

When you run a command like:
tcld n cf exp -f <path for your json export> -n <namespace>

It can print:
rpc error: code = Unauthenticated desc = request not authenticated

It'd be nice to add a line about "try tcld login

Describe the solution you'd like

Just adding a line about trying tcld login in access failure messages.

It'd be also nice to extend the documentation at:
https://docs.temporal.io/cloud/tcld/login