Fixed wrong documentation for BLUETOOTH_SERVICE.

The documentation was incorrectly stating that getSystemService() would
return a BluetoothAdater for Context.BLUETOOTH_SERVICE. The actual
return type is BluetoothManager.
diff --git a/core/java/android/content/Context.java b/core/java/android/content/Context.java
index 39a70be..f7566bb 100644
--- a/core/java/android/content/Context.java
+++ b/core/java/android/content/Context.java
@@ -2819,7 +2819,7 @@
 
     /**
      * Use with {@link #getSystemService} to retrieve a
-     * {@link android.bluetooth.BluetoothAdapter} for using Bluetooth.
+     * {@link android.bluetooth.BluetoothManager} for using Bluetooth.
      *
      * @see #getSystemService
      */