[public] Added metadata.

Author: DanilAndreev

Diff for: public/index.html

@@ -5,10 +5,8 @@
     <link rel="icon" href="%PUBLIC_URL%/favicon.png"/>
     <meta name="viewport" content="width=device-width, initial-scale=1"/>
     <meta name="theme-color" content="#1976d2"/>
-    <!--    <meta-->
-    <!--      name="description"-->
-    <!--      content="Web site created using create-react-app"-->
-    <!--    />-->
+    <meta property="og:image" content="https://github.com/material-docs/material-docs/blob/master/images/MaterialDocsLogoIcon.png?raw=true"/>
+    <meta property="og:site_name" content="Material Docs"/>
     <link rel="apple-touch-icon" href="%PUBLIC_URL%/logo.svg"/>
     <!--
       manifest.json provides metadata used when your web app is installed on a