add sso to readme

README.md

@@ -11,7 +11,7 @@
 * **Backups**: Yes
 * **Email**: No
 * **Tests**: No
-* **SSO**: No
+* **SSO**: Yes
 
 <!-- endmetadata -->
 
@@ -40,5 +40,24 @@ Then redeploy with `abra app deploy YOURAPPDOMAIN --force`.
 Now when you login as your user, and visit https://cryptpad.cctest.autonomic.zone/admin/,
 you should be able to access the admin interface for this cryptpad instance. 
 
+## SSO
+
+To enable SSO, run `abra app config YOURAPPDOMAIN` and set `SSO_ENABLED=true`. On the next deploy, the [CryptPad SSO plugin](https://github.com/cryptpad/sso) will be installed automatically.
+
+You also need to configure the remaining SSO environment variables for your OIDC provider:
+
+- `SSO_PROVIDER_NAME` — display name shown on the login button (e.g. `Keycloak`, `Authentik`)
+- `SSO_OIDC_URL` — OIDC discovery URL for your provider
+- `SSO_CLIENT_ID` — OAuth2 client ID
+- `SSO_JWT_ALG` — JWT signing algorithm (e.g. `RS256`)
+
+The client secret is stored as a Docker secret. Insert it with:
+
+```
+abra app secret insert YOURAPPDOMAIN sso_client_s v1 YOUR_CLIENT_SECRET
+```
+
+Then deploy (or redeploy) to apply: `abra app deploy YOURAPPDOMAIN --force`.
+
 [`abra`]: https://git.coopcloud.tech/coop-cloud/abra
 [`coop-cloud/traefik`]: https://git.coopcloud.tech/coop-cloud/traefik