docs: add example how to customize the conftest command

[pokgak]

following up from this thread: https://atlantis-community.slack.com/archives/C5MGGAV0C/p1668413216626419

• mention conftest --update flag to pull policies from remote sources
• add example how to customize conftest command to be able to run policy checks against Terraform (*.tf) files

[jamengual]

Thanks for the contribution @pokgak

[nitrocode]

I added some comments. Thank you so much for the contribution!

[pokgak]

Updated the PR. Thanks for the review @nitrocode @jamengual.

[pokgak]

Not sure why the links check failed. I don't have issues accessing all the URLs when I copy pasted them to my browser.

[nitrocode]

I don't understand why but the tests are failing because it thinks the following link returns a 403

https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_policies_examples_s3_rw-bucket.html

[nitrocode]

Lets remove the url that is causing the ci issues

[pokgak]

@nitrocode it seems like right now the link tests still fail, now due to links that already existed before from pages that I didn't touch in this PR.

[nitrocode]

The ci script runs across the entire source code, not just in the files affected by the pr.

https://github.com/runatlantis/atlantis/blob/main/.circleci/config.yml

Other prs have passing tests so I'm unsure why this is happening.

cc @runatlantis/maintainers what do you folks think?

[pokgak]

Looks like the link tests passes now after the merge.

[nitrocode]

Thank you @pokgak for being patient with us while we fixed the test issues. Please feel free to contribute more documentation PRs. I'm sure the next one will be much faster.

[albertorm95]

Do this still works?
add example how to customize conftest command to be able to run policy checks against Terraform (*.tf) files

I'm getting unable to unmarshal conftest output

• [Documentation] - Update Section running-policy-check-against-terraform-source-code #4092