Add comment for player rectangle initialization

Hadn't come across Rectangle struct till now thought this would help other people too.

examples/core/core_2d_camera.c

@@ -30,6 +30,7 @@ int main(void)
 
     InitWindow(screenWidth, screenHeight, "raylib [core] example - 2d camera");
 
+    //Rectangle rect = { x, y, width, height}
     Rectangle player = { 400, 280, 40, 40 };
     Rectangle buildings[MAX_BUILDINGS] = { 0 };
     Color buildColors[MAX_BUILDINGS] = { 0 };