Update README.md

README.md

@@ -3,6 +3,7 @@
 The CubeSat Simulator https://github.com/alanbjohnston/CubeSatSim/wiki is a low cost satellite emulator that run on solar panels and batteries, transmits UHF radio telemetry, has a 3D printed frame, and can be extended by additional sensors and modules.  This project is sponsored by the not-for-profit [Radio Amateur Satellite Corporation, AMSAT®](https://amsat.org).
 
 Requires:
+- Raspbian Stretch or Buster, full desktop or Lite 
 - wiringpi
 - git
 - libasound2-dev
@@ -10,7 +11,7 @@ Requires:
 - Direwolf
 - rpitx
 
-See the Wiki Software Install page for more details: https://github.com/alanbjohnston/CubeSatSim/wiki/Software-Install. To build and run the software on a Raspberry Pi 3B, 3B+, or Pi Zero W:
+See the Wiki Software Install page for more details: https://github.com/alanbjohnston/CubeSatSim/wiki/Software-Install. To build and run the software on a Raspberry Pi 3B, 3B+, or Pi Zero W (Does NOT work on a Pi 4 since rpitx does not work on it yet):
 
 `sudo apt-get install wiringpi, git, libasound2-dev`