Add the anchors to the diff in addition to the full preview #96
Description
For example, w3ctag/privacy-principles#44 links to https://pr-preview.s3.amazonaws.com/jyasskin/privacy-principles/pull/44.html#parties and https://pr-preview.s3.amazonaws.com/w3ctag/privacy-principles/44/dc93f38...jyasskin:fd77d35.html, meaning you have to scroll the diff to get to the changes, even though https://pr-preview.s3.amazonaws.com/w3ctag/privacy-principles/44/dc93f38...jyasskin:fd77d35.html#parties would go straight there.