x230: README: mention the need for a different computer for external flashing

x230/README.md

@@ -153,6 +153,7 @@ is used by some cheap memory programmers.
 The one we describe can be bought at
 [aliexpress](http://www.aliexpress.com/item/Free-Shipping-CH341A-24-25-Series-EEPROM-Flash-BIOS-DVD-USB-Programmer-DVD-programmer-router-Nine/32583059603.html),
 but it's available [elsewhere](https://geizhals.eu/?fs=ch341a) too.
+This means you need a different computer running a Linux based system here.
 Also, we don't use the included 3,3V power output (provides too little power),
 but a separate power supply. If you don't have any, consider getting a AMS1117
 based supply for a second USB port (like [this](https://de.aliexpress.com/item/1PCS-AMS1117-3-3V-Mini-USB-5V-3-3V-DC-Perfect-Power-Supply-Module/32785334595.html) or [this](https://www.ebay.com/sch/i.html?_nkw=ams1117+usb)).