Update README.MD

Author: MotionDevelopment123

README.MD

@@ -8,6 +8,8 @@ Motion-Shell is a replacement shell tool aimed at turning Windows into a expiera
 - Playnite.
   - Starts Playnite in fullscreen mode with a splash video of choice shown, when switching to desktop mode or closing Playnite the Windows-Shell is launched and closed again if you return to Fullscreen mode
   - Playnite without a splash video (Installs same files as the Splash version to allow easy switching between the 2 but if set to be without the Splash video, the Playnite.exe is set directly as the Shell program).
+- Customer Shell (coming in Beta 4)
+  - Allows you to select a custom exe program that will launch as the shell and once closed will launch the Windows-Shell or alternative action such as signing out the account.
 
 This is a Beta release, some features are missing such as:
 - ~~Uninstaller~~ Initial version included with beta 3