CLI env vars docs no longer accurate

[cretz]

Temporal Affiliation

• I am a Temporal employee

Page URL

https://docs.temporal.io/cli#environment-variables

Content Issue

https://docs.temporal.io/cli#environment-variables is no longer accurate, https://docs.temporal.io/develop/environment-configuration contains the accurate set of environment variables (though we still support some of the old ones for compat reasons, we don't need to document them).