style(@schematics/angular): minor improvements in ngsw-config.json

Author: gkalpak

packages/schematics/angular/service-worker/files/ngsw-config.json

@@ -1,24 +1,26 @@
 {
   "index": "/index.html",
-  "assetGroups": [{
-    "name": "app",
-    "installMode": "prefetch",
-    "resources": {
-      "files": [
-        "/favicon.ico",
-        "/index.html",
-        "/*.css",
-        "/*.js"
-      ]
+  "assetGroups": [
+    {
+      "name": "app",
+      "installMode": "prefetch",
+      "resources": {
+        "files": [
+          "/favicon.ico",
+          "/index.html",
+          "/*.css",
+          "/*.js"
+        ]
+      }
+    }, {
+      "name": "assets",
+      "installMode": "lazy",
+      "updateMode": "prefetch",
+      "resources": {
+        "files": [
+          "/assets/**"
+        ]
+      }
     }
-  }, {
-    "name": "assets",
-    "installMode": "lazy",
-    "updateMode": "prefetch",
-    "resources": {
-      "files": [
-        "/assets/**"
-      ]
-    }
-  }]
-}
+  ]
+}