With the removal of the side switch from the new iPad Air 2, Apple has added separate mute and rotation buttons to the iOS 8.1 Control Center to replace the missing functionality, exclusive to the new device.
The switch itself has had something of an identity crisis over the years, with Apple originally debuting it as a rotation lock when the iPad was first released, then later unceremoniously changing it to a mute switch before finally giving users a choice as to its function.
The iOS Control Center has traditionally included a button to toggle whichever of the two functions was not assigned to the side switch; Apple has now removed the switch and simply added controls for both settings into the Control Center.