Amazon has updated its Kindle app with bug fixes and a couple of small but substantial user interface tweaks for Android tablet users. You can now adjust a a book's margins and line spacing to your liking, as well as view two pages side-by-side in landscape mode. While these are common features in other ebook reading apps, having these improvements in Kindle — the 800-pound gorilla of the ebook world — will be great for those who are invested in the platform. As usual, just sign in to Google Play on your device and either download the app or check for the update.