cleaned up some junk in header files
diff --git a/gyro_board/src/usb/data_struct.h b/gyro_board/src/usb/data_struct.h
index 64c9631..9e97950 100644
--- a/gyro_board/src/usb/data_struct.h
+++ b/gyro_board/src/usb/data_struct.h
@@ -1,6 +1,8 @@
// This isn't really a header file. It's designed to be #included directly into
// other code (possibly in a namespace or whatever), so it doesn't have include
// guards.
+// This means that it can not #include anything else because it (sometimes) gets
+// #included inside a namespace.
// In the gyro board code, fill_packet.h #includes this file.
// In the fitpc code, frc971/input/gyro_board_data.h #includes this file.