Initialize auto rewind time and update description

android/app/src/main/java/com/audiobookshelf/app/data/DeviceClasses.kt

@@ -126,7 +126,7 @@ data class DeviceSettings(
         autoSleepTimerEndTime = "06:00",
         sleepTimerLength = 900000L, // 15 minutes
         autoSleepTimerAutoRewind = false,
-        autoSleepTimerAutoRewindTime = 300000L,
+        autoSleepTimerAutoRewindTime = 300000L, // 5 minutes
         disableSleepTimerFadeOut = false,
         disableSleepTimerResetFeedback = false
       )

android/app/src/main/java/com/audiobookshelf/app/device/DeviceManager.kt

@@ -39,6 +39,10 @@ object DeviceManager {
     if (deviceData.deviceSettings?.shakeSensitivity == null) {
       deviceData.deviceSettings?.shakeSensitivity = ShakeSensitivitySetting.MEDIUM
     }
+    // Initialize auto sleep timer auto rewind added in v0.9.64
+    if (deviceData.deviceSettings?.autoSleepTimerAutoRewindTime == null) {
+      deviceData.deviceSettings?.autoSleepTimerAutoRewindTime = 300000L // 5 minutes
+    }
   }
 
   fun getBase64Id(id:String):String {