fix: clarify default jwks (#1709)

Author: vinckr

docs/oauth2-oidc/jwt-access-token.mdx

@@ -119,6 +119,21 @@ http://{project.slug}.projects.oryapis.com/.well-known/jwks.json
 
 All necessary keys are available there.
 
+#### Default JSON Web Key Sets
+
+In Ory, JSON Web Key (JWK) endpoints require a `set-id`. This `set-id` corresponds to the specific set of keys you want to
+interact with. If you're looking to interact with the default keys used by Ory, you can use the following `set-id` values:
+
+- `hydra.openid.id-token`: This set contains the keys used for signing OpenID Connect ID Tokens.
+- `hydra.jwt.access-token`: This set contains the keys used for signing JWT Access Tokens.
+
+You can use these `set-id` values with the JWK endpoints to retrieve, rotate, or otherwise manage these default key sets. For
+example, to retrieve the OpenID Connect ID Token key set, you would use the GET /admin/keys/{set} endpoint with
+`hydra.openid.id-token` as the `{set}` parameter. This information is particularly useful when rotating keys, as described in the
+[documentation on key rotation](https://www.ory.sh/docs/hydra/self-hosted/secrets-key-rotation). Remember, these are the default
+key sets used by Ory. If you've configured Ory to use different key sets, you'll need to use the `set-id` values corresponding to
+your custom key sets.
+
 ## Custom consent UI and custom claims for (JWT) access token
 
 Using the following code during, you can add custom claims to every access token during consent acceptance