Updated README

Author: csharpfritz

sessions/Season-06/README.md

@@ -9,3 +9,4 @@ This is based on the .NET MAUI workshop, available at https://github.com/dotnet-
 | 0601 | [Introduction to .NET MAUI](0601/README.md) |
 | 0602 | [Overview of MAUI and Data](0602/README.md) |
 | 0603 | [MVVM and App Navigation](0603/README.md) |
+| 0604 | [Platform Features and Themes](0604/README.md) |