Add favicon

[BravishkaSkytano]

Every site should have a favicon. Users will only need to add one file to the site's root directory.

[supun-io]

Apologies for the 2-year delay. This would limit the favicon to be .png, wouldn't it? I think it would be better to not have this, as all browsers default to favicon.ico. If the user needs something else, he'd add a custom line like this.

Open for feedback.

[BravishkaSkytano]

It's been a while since I used this theme, however, I do recall trying to use a favicon.ico and it didn't work. You could set it as a config variable instead, I suppose.

favicon: /assets/favicon.ico

<link rel="icon" type="image/png" sizes="32x32" href="{{ site.favicon }}">