Add linmath.h to readme dependency list

README.md

@@ -58,6 +58,8 @@ GLFW bundles a number of dependencies in the `deps/` directory.
    examples
  - An OpenGL 3.2 core loader generated by
    [glad](https://github.com/Dav1dde/glad) for examples using modern OpenGL
+ - [linmath.h](https://github.com/datenwolf/linmath.h) for linear algebra in
+   examples
 
 
 ## Changelog