Jenkinsfile: fix YAML syntax
diff --git a/Jenkinsfile b/Jenkinsfile
index a81da79..8a35eb4 100644
--- a/Jenkinsfile
+++ b/Jenkinsfile
@@ -49,13 +49,13 @@
       - name: m2-repo
         emptyDir: {}
   - name: jnlp
-      volumeMounts:
-        - name: volume-known-hosts
-          mountPath: /home/jenkins/.ssh
-      volumes:
-        - name: volume-known-hosts
-          configMap:
-            name: known-hosts
+    volumeMounts:
+      - name: volume-known-hosts
+        mountPath: /home/jenkins/.ssh
+    volumes:
+      - name: volume-known-hosts
+        configMap:
+          name: known-hosts
 """
        }
     }