From there, you can do some basic customization of the buttons, including specifying the
content that will be included when users post. When you configure the URL option for your
button, we’ll use that URL to include a preview of the page based on its title and meta
description tags. If you don’t specify a link, we’ll take our best guess by including the page
on which you placed the button. Likewise, when you set up an image URL, we’ll add a thumbnail
of that image to the post your users create. If you prefer to set up your buttons by hand,
these options and more are also available through our JavaScript API -- for more details,
check out our spec.
