Update README and add updates tab screenshot

Author: dragunoff

README.md

@@ -1,9 +1,11 @@
 # OpenRA Launcher
 
-A desktop application for launching OpenRA mods and tracking new releases and playtests. Runs on Linux and Windows - head over to the releases page to [download the latest release](https://github.com/dragunoff/OpenRA-Launcher/releases/latest).
+A desktop application for launching OpenRA mods and tracking new releases and playtests. Runs on Linux (as an AppImage) and Windows (a poratble exe) - head over to the releases page to [download the latest release](https://github.com/dragunoff/OpenRA-Launcher/releases/latest).
 
 ![List of installed mods](./screenshots/screenshot-mods.png)
 
+![List of new realeases and playtests to download](./screenshots/screenshot-updates.png)
+
 Feeback is welcome so you can [submit a bug report or feature request](https://github.com/dragunoff/OpenRA-Launcher/issues) on the issue tracker.
 
 glhf!