Added legal disclaimer

Author: artyuum

README.md

@@ -1,3 +1,6 @@
 # Simple-PHP-Web-Shell
 A really simple & tiny PHP Web shell for executing unix commands from web page.
 ![alt text](https://raw.githubusercontent.com/artyuum/Simple-PHP-Web-Shell/master/screenshot.png "Screenshot")
+
+## Legal disclaimer
+Usage of this script as a backdoor in order to have external access to a server you do not own without prior consent is illegal. It is the end user's responsibility to obey all applicable local, state and federal laws. Developers assume no liability and are not responsible for any misuse or damage caused by this program.