added ratings to examples

examples/shaders/shaders_texture_drawing.c

@@ -34,6 +34,8 @@ int main(void)
     const int screenHeight = 450;
 
     InitWindow(screenWidth, screenHeight, "raylib [shaders] example - texture drawing");
+*
+*   Example complexity rating: [★★☆☆] 2/4
 
     Image imBlank = GenImageColor(1024, 1024, BLANK);
     Texture2D texture = LoadTextureFromImage(imBlank);  // Load blank texture to fill on shader