Add Okta OIDC Guide

[IAmHughes]

This PR adds the Okta OIDC guide for creating an app to use OIDC with Okta and Coder.

[github-actions]

✨ Coder.com for PR #393 deployed! It will be updated on every commit.

• Host: https://codercom-n23r4c7gw-codercom.vercel.app/docs
• Last deploy status: success
• Commit: daabcc5
• Workflow status: https://github.com/cdr/docs/actions/runs/919159202

[IAmHughes]

This is ready for review. For some reason, the deploy preview seems broken for the Docs tab and I'm not sure why? @bpmct or @ericpaulsen do you know?

[ericpaulsen]

LGTM - only thing I'd recommend adding is context around Okta groups & users being already able to access Coder. No need to manually add users on the Coder side.

[IAmHughes]

Okta groups & users being already able to access Coder. No need to manually add users on the Coder side.

I'm not sure what you mean @ericpaulsen? Within Okta, if no one is assigned the application (step 3 in the guide), no one can access Coder.

[ericpaulsen]

Yes - my comment assumed that such groups & users would be assigned to the application. Apologies for the lack of clarity.

[IAmHughes]

Any ideas on the Docs tab not working in the preview deployment @ericpaulsen ?

[ericpaulsen]

Not sure. I'm not familiar with debugging the Vercel preview. In my experience, issues with the preview aren't typically indicative of an issue with the commit once merged.

[greyscaled]

@all-contributors please add @IAmHughes for bug, content, idea

[allcontributors]

@vapurrmaid

I've put up a pull request to add @IAmHughes! 🎉