embed Terraform provider docs in reference documentation (optional)

[dangrondahl]

Terraform provider documentation currently lives in `kosli-dev/terraform-provider-kosli`.
Explore embedding or linking it directly into the Mintlify reference section.

Tasks

• Evaluate options: embed generated docs vs. linking out to the provider repo
• If embedding: set up automation to sync Terraform docs on provider releases,
  similar to `update-cli-docs.yml`
• Add Terraform reference section to `docs.json` navigation
• Open PRs in relevant repos

References

• `kosli-dev/terraform-provider-kosli`
• `.github/workflows/update-cli-docs.yml`