Clarify serial_driver.md

Clarify text after talking with engineering.

Author: Amanda Butler

docs/tutorials/serial/serial_driver.md

@@ -1,6 +1,6 @@
 # Windows serial driver
 
-You can connect your board to your computer over USB. This works out of the box on Linux, macOS and Windows 10. If you are using a version of Windows earlier than Windows 10, you probably need to install a serial port driver:
+You can connect your board to your computer over USB. This works out of the box on Linux and macOS. If you are using Windows, you may need to install a serial port driver:
 
 1. Download the [Arm Mbed Windows serial port driver](http://os.mbed.com/media/downloads/drivers/mbedWinSerial_16466.exe).
 1. Plug in your Arm Mbed device over USB. It mounts as an Mbed drive.