more changes to README

Author: tcprescott

README.md

@@ -4,6 +4,8 @@ Lets you easily load a ROM onto your sd2snes by using usb2snes!  Great for Rando
 
 ## Building it yourself
 
+You'll need a working Python 3.6 environment.  I've only tested this with Python 3.6.
+
 1. Install pyinstaller so you can build the exe, which is a packaged python distribution (no dependancy on python) - `pip install pyinstaller`
 2. Install the required packages, hopefully requirements.txt is complete - `pip install -r requirements.txt`
 3. Build the project - `pyinstaller --onefile src/romloader.py`