Added small MSYS2 installation guide.

Working-on-Windows.md

@@ -4,6 +4,14 @@
 The fastest way to get a game setup on windows with MinGW or Visual Studio is to use premake.
 See [raylib-extras/game-premake](https://github.com/raylib-extras/game-premake) for instructions
 
+#### Installing raylib via msys2
+
+You can download and install raylib using the [msys2](https://www.msys2.org/) package manager (pacman):
+
+      pacman -S mingw-w64-x86_64-raylib
+
+---
+
 #### Installing and building raylib via vcpkg
 
 You can download and install raylib using the [vcpkg](https://github.com/Microsoft/vcpkg) dependency manager: