fix(index.html): remove duplicated meta tag (#1065)

* remove duplicated meta tag for `theme-color`

Author: USSDlover

material.angular.io/src/index.html

@@ -11,7 +11,6 @@
   <meta name="apple-mobile-web-app-capable" content="yes">
   <meta name="apple-mobile-web-app-status-bar-style" content="translucent">
   <meta name="mobile-web-app-capable" content="yes">
-  <meta name="theme-color" content="#3F50B5">
   <meta name="description" content="UI component infrastructure and Material Design components for mobile and desktop Angular web applications.">
   <meta name="keywords" content="angular, material design, material, angular material, web, ui, components, responsive, accessibility, typescript, css, mobile web, open source">
   <meta name="author" content="Angular Components Team">