Update README.md

Author: BigJk

README.md

@@ -49,6 +49,7 @@ or a letter that the group found to little character sheets of your players to u
 
 You can find the latest version on the release page:
 - https://github.com/BigJk/snd/releases
+- **Linux / Mac**: You might need to ``chmod +x`` the executable before you can run it!
 
 ## Printer Requirements