docs/playgrounds: add links to SSO playground (#10877)

Added info about Grafana SSO playground to playgrounds docs.

---------

Signed-off-by: Max Kotliar <kotlyar.maksim@gmail.com>
Co-authored-by: Max Kotliar <mkotlyar@victoriametrics.com>

docs/guides/grafana-vmauth-openid-configuration/README.md

@@ -4,6 +4,8 @@ Those tokens can include information about the user and their tenant, which vmau
 
 This guide walks through configuring Grafana with OIDC to query metrics from both single-node and cluster deployments of VictoriaMetrics.
 
+> Public playground configured by using this guide can be found here: [Grafana SSO Playground](https://docs.victoriametrics.com/playgrounds/#grafana-sso-playground)
+
 ## Prerequisites
 
 * [Docker](https://docs.docker.com/engine/install/) and [docker compose](https://docs.docker.com/compose/) must be installed.
@@ -460,4 +462,3 @@ While in VictoriaMetrics single `vmauth-single` must apply the `team=admin` labe
 ## Summary
 
 In this guide, we demonstrated how to set up vmauth with OIDC authorization using Keycloak as the identity provider. We also showed how to provide multi-tenant access to your metrics stored in VictoriaMetrics, single-node or cluster, using Grafana and vmauth with OIDC authorization enabled.
-

docs/playgrounds/README.md

@@ -93,6 +93,20 @@ Try viewing available dashboards or just browse via Grafana's explore page to qu
 
 ![Screenshot of Grafana Dashboard](grafana-node-exporter.webp)
 
+## Grafana SSO Playground
+
+- Try it: <https://play-grafana-sso.victoriametrics.com/>
+
+This playground showcases vmauth integration with Keycloak as an SSO provider to enforce data visibility for different users.
+See this guide for details: [Setup vmauth - Multi-Tenant Access with Grafana & OIDC](https://docs.victoriametrics.com/guides/grafana-vmauth-openid-configuration/)
+
+Credentials for login:
+
+- `developer` / `developer`
+- `platform` / `platform`
+
+Both users have their access limited to show data which is necessary for their role, so you can see how vmauth and Keycloak work together to enforce multi-tenant access control.
+
 ## VMAnomaly Playground
 
 VMAnomaly analyzes metrics, logs, or traces using VictoriaMetrics' built-in anomaly detection model to generate an [anomaly score](https://docs.victoriametrics.com/anomaly-detection/faq/#what-is-anomaly-score). An `anomaly_score > 1` indicates an anomalous condition that deserves attention.