Fixes #93 - Delete optgroup element and add HTML code

[cevdetta]

Fixes #93
As I mentioned in here Delete opgroup element, it's unnecessary and should be deleted, I've added new HTML code that has select>optgroup, I didn't delete optgroup but I think it should be deleted to.

[cevdetta]

As you can see on MDN: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/optgroup

<label for="dino-select">Choose a dinosaur:</label>
<select id="dino-select">
  <optgroup label="Theropods">
    <option>Tyrannosaurus</option>
    <option>Velociraptor</option>
    <option>Deinonychus</option>
  </optgroup>
  <optgroup label="Sauropods">
    <option>Diplodocus</option>
    <option>Saltasaurus</option>
    <option>Apatosaurus</option>
  </optgroup>
</select>

and at the end it talks about which element or elements can be parent or child and it's basically like this: select>optgroup>option.