Update VAO comment

src/main.cc

@@ -31,7 +31,7 @@ struct App {
   SDL_GLContext context;
   SDL_Event     event;
 
-  // Defines the different attributes in the vertex data and how to access them.
+  // VAO is an object that stores the state needed to supply the GPU with the vertex data.
   // Think of it as a specification or a C struct that defines the types of data stored for the
   // vertex array including the attributes for each vertex as well the indices buffer if it exists.
   GLuint        vao;