Last month Apple released iOS 8.1 and today they continue to bring us version 8.1.1. With version 8.1.1 we will not have major changes in the interface or use features, instead Apple focuses on fixing bugs as well as improving performance, increasing stability on older devices. A5 CPU like iPad 2, iPad Mini and iPhone 4S.
To be able to update immediately, go to Settings > General > Software Update and download the update to proceed with the upgrade. On my iPhone 5C, the update is difficult to understand, up to 1.5GB.
** Note: If your iOS device is less than 50% battery, the device will ask you to plug in the charger before allowing to download the update. Of course, a good Wi-Fi connection is needed to make the update as perfect as possible. Data backup should be backed up to prevent data loss risks if something goes wrong.