Readme modified, osx screenshots added

Author: Akhsarbek Gozoev

README.md

@@ -27,6 +27,10 @@ I have ported to Windows, X11, and Soso. Just look at (doomgeneric_win.c or doom
 
 Note that X11 port is not efficient since it generates pixmap by XDrawPoint. It can be further improved by using X11 extensions.
 
+## OSX
+
+![OSX](screenshots/osx.png)
+
 ## Windows
 ![Windows](screenshots/windows.png)