nx: Build DocumentsUI

* Normally, this would normally be a platform decision, to build,
  or not to build an non-controller navigable app on ATV builds.

* But we are the weird-ass edge case (as always), in that we are
  an ATV device with touch-input, meaning this application will work
  on this device.

Change-Id: I2f32ba14d522f0dc81db13ef76e8f52a0b151770

device.mk

@@ -114,6 +114,11 @@ PRODUCT_PACKAGES += \
 PRODUCT_PACKAGES += \
     DeviceSettingsNX
 
+# DocumentsUI
+# We are the exception, being an ATV device with touch
+PRODUCT_PACKAGES += \
+    DocumentsUI
+
 # GMS
 ifeq ($(WITH_GMS),true)
 WITH_GMS_COMMS_SUITE := false