Add Catalina theme

Author: t1m0thyj

README.md

@@ -10,3 +10,7 @@ Themes ported from macOS to WinDynamicDesktop
 **Solar Gradients**
 
 ![Solar Gradients](images/Solar_Gradients.jpg)
+
+## [Catalina](https://github.com/t1m0thyj/WDD-mac-themes/releases/tag/catalina)
+
+![Catalina](images/Catalina.jpg)