Add raylib-cr (#621)

README.md

@@ -277,6 +277,7 @@ described in [RFC 8032]
  * [crystal-imgui-sfml](https://github.com/oprypin/crystal-imgui-sfml) - Bindings to integrate [Dear ImGui](https://github.com/ocornut/imgui) into an [SFML](https://www.sfml-dev.org/) project
  * [entitas.cr](https://github.com/spoved/entitas.cr) - A Entity Component System Framework for Crystal
  * [MyECS](https://github.com/konovod/myecs) - A Sparse Entity Component System Framework for Crystal
+ * [Raylib-cr](https://github.com/sol-vin/raylib-cr) - Direct bindings to [Raylib](https://raylib.com), which supports Linux, Windows, and Mac
  * [SDL-Crystal-Bindings](https://github.com/Hadeweka/SDL-Crystal-Bindings) - Direct (unsafe) bindings to [SDL2](https://www.libsdl.org/), intended for writing own game libraries
 
 ## GUI Development