docs: add more specific steps and information about oidc refresh tokens (#18336)

closes https://github.com/coder/coder/issues/18307

relates to https://github.com/coder/coder/pull/18318

preview:
-
[refresh-tokens](https://coder.com/docs/@18307-refresh-tokens/admin/users/oidc-auth/refresh-tokens)
-
[configuring-okta](https://coder.com/docs/@18307-refresh-tokens/tutorials/configuring-okta)
~(not sure why @Emyrk 's photo is so huge there though)~ ✔️
- [x] removed from
[idp-sync](https://coder.com/docs/@18307-refresh-tokens/admin/users/idp-sync)

to do:
- move keycloak
- add ping federate and azure
- edit text (possibly placeholders for now - I want to see how it all
relates and edit it again. right now, there's a note about the same
thing in every section in way that's not super helpful/necessary)
- ~convert some paragraphs to OL~ calling this out of scope for now

---------

Co-authored-by: EdwardAngert <17991901+EdwardAngert@users.noreply.github.com>

docs/admin/infrastructure/architecture.md

@@ -108,10 +108,10 @@ Users will likely need to pull source code and other artifacts from a git
 provider. The Coder control plane and workspaces will need network connectivity
 to the git provider.
 
-- [GitHub Enterprise](../external-auth.md#github-enterprise)
-- [GitLab](../external-auth.md#gitlab-self-managed)
-- [BitBucket](../external-auth.md#bitbucket-server)
-- [Other Providers](../external-auth.md#self-managed-git-providers)
+- [GitHub Enterprise](../external-auth/index.md#github-enterprise)
+- [GitLab](../external-auth/index.md#gitlab-self-managed)
+- [BitBucket](../external-auth/index.md#bitbucket-server)
+- [Other Providers](../external-auth/index.md#self-managed-git-providers)
 
 ### Artifact Manager (Optional)