add svg favicon (#648)

Author: Arhell

_layouts/bootstrap.html

@@ -26,7 +26,9 @@
     <link rel="apple-touch-icon" sizes="180x180" href="/favicons/apple-touch-icon.png">
     <link rel="icon" type="image/png" sizes="32x32" href="/favicons/favicon-32x32.png">
     <link rel="icon" type="image/png" sizes="16x16" href="/favicons/favicon-16x16.png">
-    <link rel="icon" type="image/png" sizes="16x16" href="/favicons/favicon.ico">
+    <link rel="icon" type="image/svg+xml" href="/favicons/favicon.svg">
+    <link rel="icon" type="image/png" href="/favicons/favicon.png">
+    <link rel="icon" type="image/png" href="/favicons/favicon.ico">
     <link rel="manifest" href="/favicons/site.webmanifest">
     <link rel="mask-icon" href="/favicons/safari-pinned-tab.svg" color="#236BFD">
     <meta name="msapplication-config" content="/favicons/browserconfig.xml" />