Add to your HTML <head>:

<link rel="icon" type="image/x-icon" href="/favicon.ico">
<link rel="icon" type="image/png" sizes="32x32" href="/favicon-32.png">
<link rel="icon" type="image/png" sizes="16x16" href="/favicon-16.png">
<link rel="apple-touch-icon" sizes="128x128" href="/favicon-128.png">