add elastic header example

Author: yyx990803

src/examples/elastic-header.md

@@ -0,0 +1,7 @@
+---
+title: Elastic Header
+type: examples
+order: 7
+---
+
+<iframe width="100%" height="500" src="http://jsfiddle.net/yyx990803/2eg8kbyk/embedded/result,html,js,css" allowfullscreen="allowfullscreen" frameborder="0"></iframe>

src/examples/hackernews.md

@@ -1,7 +1,7 @@
 ---
 title: HackerNews Clone
 type: examples
-order: 9
+order: 10
 ---
 
 > This is a HackerNews clone built upon HN's official Firebase API, and using Webpack + vue-loader for the build setup.

src/examples/select2.md

@@ -1,7 +1,7 @@
 ---
 title: Custom Directive
 type: examples
-order: 7
+order: 8
 ---
 
 > In this example we are integrating a 3rd party jQuery plugin (select2) by wrapping it inside a custom directive.

src/examples/todomvc.md

@@ -1,7 +1,7 @@
 ---
 title: TodoMVC
 type: examples
-order: 8
+order: 9
 ---
 
 > This is a fully spec-compliant TodoMVC implementation in under 120 effective lines of JavaScript (excluding comments and blank lines).