centos7 build

Working-on-GNU-Linux.md

@@ -172,6 +172,14 @@ The official Arch Repository contains the `raylib` package. Install via:
 pacman -S raylib
 ```
 
+### CentOS 7
+```
+yum -y install devtoolset-9\*
+scl enable devtoolset-9 bash
+make PLATFORM=PLATFORM_DESKTOP GRAPHICS=GRAPHICS_API_OPENGL_11 -B
+```
+
+
 ## The simplest possible build command
 After installing raylib from source or package manager, you can build a project with this command (modify as necessary):
 ```