Add config option to allow disabled header title

examples/siteConfig.js

@@ -48,6 +48,7 @@ const siteConfig = {
   ],
   /* path to images for header/footer */
   headerIcon: "img/docusaurus.svg",
+  disableHeaderTitle: false /* disable title text in header (only show headerIcon) */,
   footerIcon: "img/docusaurus.svg",
   favicon: "img/favicon.png",
   /* default link for docsSidebar */

lib/core/nav/HeaderNav.js

@@ -113,9 +113,10 @@ class HeaderNav extends React.Component {
           <header>
             <a href={this.props.baseUrl}>
               <img src={this.props.baseUrl + siteConfig.headerIcon} />
-              <h2>
-                {this.props.title}
-              </h2>
+              {!this.props.config.disableHeaderTitle &&
+                <h2>
+                  {this.props.title}
+                </h2>}
             </a>
             {this.renderResponsiveNav()}
           </header>