`client_id` and `client_secret` is undocumented for `vault_identity_oidc_client`

[aucampia]

vault_identity_oidc_client provides client_id and client_secret as output:

https://github.com/hashicorp/terraform-provider-vault/blob/9f1b371673291df05abc0247fdea0fcb0bc060ed/vault/resource_identity_oidc_client.go#L68-L78

But it is not documented as far as I can tell:

https://github.com/hashicorp/terraform-provider-vault/blob/9f1b371673291df05abc0247fdea0fcb0bc060ed/website/docs/r/identity_oidc_client.html.md

[jgrumboe]

I can do this, if that's fine.