Update README.md

Author: PaulZC

README.md

@@ -9,7 +9,7 @@ If you need to install the application, see the [Installation Section](#installa
 
 ## Notes:
 
-From v1.6.0, this GUI does not contain a copy of ```esptool.py```. Instead the latest ```esptool.py``` is installed and used by the build workflow. If you want to run ```RTK_Firmware_Uploader.py``` locally, you will need to ```pip install esptool``` first.
+From v1.6.0, this GUI does not contain a copy of ```esptool.py```. Instead the latest ```esptool.py``` is installed and used by the build workflow. If you want to run ```RTK_Firmware_Uploader.py``` locally, you will need to ```pip install esptool``` first. v1.6.0 of the GUI was written for and tested with v4.7.0 of esptool.
 
 # Using the RTK Firmware Uploader