How to add Favicon?
Upload your icon in public folder of your website and make sure you're able to access that favicon via https://yourwebsite/favicon.[png/jpg]
Once you see your favicon getting loaded in above URL, use below code and put that URL instead of [YOUR_FAVICON_URL] withj [EXT] as PNG or JPG depending upon extension of your image file.
<link rel="icon" href="[YOUR_FAVICON_URL]" type="image/[EXT]">