Reference other available versions of the template

Author: MartinHelmut

README.md

@@ -14,8 +14,11 @@ After using this template to create your own repository, it is time to first run
 
 ## Other versions
 
-There is also a [SDL2 version using the SDL2 Renderer](https://github.com/MartinHelmut/cpp-gui-template-sdl2) instead of
-OpenGL specifically, but it does not support multi-viewports or detached widgets.
+There are other versions of this template:
+
+- [SDL3 & OpenGL](https://github.com/MartinHelmut/cpp-gui-template-sdl3-opengl)
+- [SDL3 Renderer](https://github.com/MartinHelmut/cpp-gui-template-sdl3)
+- [SDL2 Renderer](https://github.com/MartinHelmut/cpp-gui-template-sdl2)
 
 ## Disclaimer