Fix scale matrix example command

[jneidel]

glm::mat4 myScalingMatrix = glm::scale(2.0f, 2.0f ,2.0f);
// -> to
glm::mat4 myScalingMatrix = glm::scale(glm::mat4(1), glm::vec3(2,2,2));

The given glm::scale did not work for me, the docs request the latter format. Which works fine now.

• glm 0.9.9.8-1
• mesa 21.2.1-1