Add supported keycloak version

Author: jmagak

artifacts/rhdh-plugins-reference/keycloak/keycloak-plugin-admin.adoc

@@ -6,17 +6,22 @@ The Keycloak backend plugin, which integrates Keycloak into {product-short}, has
 * Synchronization of Keycloak users in a realm.
 * Synchronization of Keycloak groups and their users in a realm.
 
+[NOTE]
+====
+The supported Keycloak version is `18.x`.
+====
+
 == Installation
 
 The Keycloak plugin is pre-loaded in {product-short} with basic configuration properties. To enable it, set the `disabled` property to `false` as follows:
 
 [source,yaml]
 ----
-global: 
-  dynamic: 
-    includes: 
+global:
+  dynamic:
+    includes:
       - dynamic-plugins.default.yaml
-    plugins: 
+    plugins:
       - package: ./dynamic-plugins/dist/janus-idp-backstage-plugin-keycloak-backend-dynamic
         disabled: false
 ----
@@ -87,7 +92,7 @@ The following table describes the parameters that you can configure to enable th
 | Name | Description | Default Value | Required
 
 | `baseUrl`
-| Location of the Keycloak server, such as `pass:c[https://localhost:8443/auth]`. Note that the newer versions of Keycloak omit the `/auth` context path.
+| Location of the Keycloak server, such as `pass:c[https://localhost:8443/auth]`.
 | ""
 | Yes