Jenkins config

- fixed stage declaration

Jenkinsfile

@@ -1,18 +1,20 @@
 pipeline {
     agent any
 
-    stage('Stylecheck') {
+    stages {
+        stage('Stylecheck') {
         steps {
             echo 'Checking Style...'
             sh 'npm i'
             sh 'npm i tslint --dev'
             sh 'tslint src/**/*.ts'
         }
-    }
-    stage('Build') {
-        steps {
-            echo 'Building...'
-            sh 'ng build --prod'
+        }
+        stage('Build') {
+            steps {
+                echo 'Building...'
+                sh 'ng build --prod'
+            }
         }
     }
 }