dbt Cloud CLI: add `--download-artifacts` flag

[nghi-ly]

What are you changing in this pull request and why?

Add info about new --download-artifacts flag for the dbt Cloud CLI :

• [x] https://docs.getdbt.com/reference/artifacts/dbt-artifacts#when-are-artifacts-produced
• [x] https://docs.getdbt.com/docs/cloud/configure-cloud-cli#faqs

for JIRA: https://dbtlabs.atlassian.net/browse/CLI-485

Checklist

• [x] Review the Content style guide so my content adheres to these guidelines.
• [x] For docs versioning, review how to version a whole page and version a block of content.
• [ ] Needs review from PM

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Name	Status	Preview	Comments	Updated (UTC)
docs-getdbt-com	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Jun 25, 2024 5:41pm

[nghi-ly]

we don't need this change anymore, per PM. closing.