website/docs: add instructions for deploying radius manually with docker compose (#9605)

website/docs/outposts/manual-deploy-docker-compose.md

@@ -50,3 +50,23 @@ services:
             AUTHENTIK_INSECURE: "false"
             AUTHENTIK_TOKEN: token-generated-by-authentik
 ```
+
+### RADIUS outpost
+
+```yaml
+version: "3.5"
+
+services:
+    radius_outpost:
+        image: ghcr.io/goauthentik/radius
+        # Optionally specify which networks the container should be
+        # might be needed to reach the core authentik server
+        # networks:
+        #   - foo
+        ports:
+            - 1812:1812/udp
+        environment:
+            AUTHENTIK_HOST: https://your-authentik.tld
+            AUTHENTIK_INSECURE: "false"
+            AUTHENTIK_TOKEN: token-generated-by-authentik
+```