Remove useless links and update code samples

Author: st0012

lib/index.js

@@ -11,7 +11,6 @@ const styleURL = style => `/css/code-style/${style}.css`
 const codeFiles = {
   'server-code': 'server.gb',
   'model-code': 'model.gb',
-  'db-code': 'plugin.gb'
 }
 
 axios.all(Object.keys(codeFiles).map(key => codeFiles[key]).map(file => axios.get(fileURL(file))))

public/index.html

@@ -22,12 +22,10 @@
     <nav>
       <div id="desktop-nav" class="nav-wrapper">
         <a target="_blank" href="https://github.com/goby-lang/goby"><span>GitHub</span></a>
-        <a target="_blank" href="https://goby-lang.gitbooks.io/goby/content/"><span>GitBook</span></a>
         <a id="logo-link" href="https://github.com/goby-lang/goby" target="_blank">
           <img id="logo" src="./icon/goby-logo.svg" alt="Goby Lang Logo">
         </a>
         <a target="_blank" href="https://twitter.com/goby_lang"><span>Twitter</span></a>
-        <a target="_blank" href="https://www.producthunt.com/posts/goby-language"><span>ProductHunt</span></a>  
       </div>
 
       <div id="mobile-nav" class="nav-wrapper">
@@ -68,7 +66,6 @@ <h4>Stay up to date on Goby's news</h4>
         <ul id="code-tab">
           <li id="server-code" class="active">server.gb</li>
           <li id="model-code">model.gb</li>
-          <li id="db-code">plugin.gb</li>
         </ul>
         <pre><code class="ruby" id="render-code"></code></pre>
       </div>

public/js/index.js

@@ -10452,8 +10452,7 @@ var styleURL = function styleURL(style) {
 
 var codeFiles = {
   'server-code': 'server.gb',
-  'model-code': 'model.gb',
-  'db-code': 'plugin.gb'
+  'model-code': 'model.gb'
 };
 
 _axios2.default.all(Object.keys(codeFiles).map(function (key) {