add info on stackblitz

app/3.0/docs/stack-blitz.md

@@ -0,0 +1,41 @@
+---
+title: "Polymer 3.0 on StackBlitz"
+---
+
+<!-- toc -->
+
+[StackBlitz](https://stackblitz.com) is an online editor for web projects. You can use StackBlitz to prototype and preview Polymer elements and apps without a build step.
+
+StackBlitz transpiles ES6 to ES5, so samples with Polymer 3.0 code can run on any browser. You can install dependencies using npm, and import them with Node.js-style module resolution (`import {PolymerElement} from '@polymer/polymer/polymer-element.js'`). 
+
+You can still use Polymer 3.0 in other online code editors, like [Plunker](https://plnkr.co/) or [jsbin](https://jsbin.com/), but you may need to use non-standard paths to import dependencies, and the code may not run on older browsers. 
+
+Here's a [StackBlitz template for Polymer 3.0 to help you get started](https://stackblitz.com/edit/start-polymer3?file=start-polymer3.js). 
+
+Please note that at the time of writing, StackBlitz requires an `index.js` and `index.html` file to be present in the root folder for all JavaScript projects. You'll need to import JavaScript modules, such as elements, from `index.js`:
+
+index.js {.caption}
+
+```js
+import `my-app.js`;
+```
+
+index.html {.caption}
+
+```html
+<!-- StackBlitz compiles es6 code to es5. Include custom elements adapter to make code work in es6-native browsers -->
+<script src="./node_modules/@webcomponents/webcomponentsjs/custom-elements-es5-adapter.js"></script>
+<!-- Include WebComponents polyfills -->
+<script src="./node_modules/@webcomponents/webcomponentsjs/webcomponents-loader.js"></script>
+<my-app></my-app>
+```
+
+my-app.js {.caption}
+
+```js
+import PolymerElement from '@polymer/polymer/polymer-element.js';
+class MyApp extends PolymerElement {
+  ...
+}
+window.customElements.define('my-app', MyApp);
+```

app/3.0/nav.yaml

@@ -150,9 +150,6 @@
   - title: Publish your elements
     path: /3.0/docs/tools/publish
     indent: True
-  - title: Web services
-    path: /3.0/docs/tools/services
-    indent: True
   - title: polymer.json specification
     path: /3.0/docs/tools/polymer-json
     indent: True
@@ -164,6 +161,9 @@
   - title: Glossary
     path: /3.0/docs/glossary
     indent: True
+  - title: Polymer 3.0 on StackBlitz
+    path: /3.0/docs/stackblitz
+    indent: True
   - endheader: True
   - header: API Reference
   - title: API Reference