HTML and CSS cleaning

[MikeFernandez-Pro]

I moved scripts into a separated folder "scripts", same for "styles" for CSS styles and restructured the HTML :

• Added header, main, footer,
• Placed div into sections with an h2 title

[GuillaumeDua]

Thanks for your contribution,
there are a few minor changes requested as review comment down below to make it great

Once accepted, we might reuse some of those file not only for divs_html_elements test but also others.

You might wanna move some folders :

• styles/ so it becomes tests/styles/
• scripts/awesome-doc-configuration.js so it becomes `tests/scripts/awesome-doc_default-configuration.js

and then, for reusability purpose, refactorhttps://github.com/GuillaumeDua/awesome-doc-code-sections/blob/ce4493eadb3d899e209f550a2acf8fb424d51f59/tests/per_usage/custom_html_elements/index.html so it also gets benefits from it.

[GuillaumeDua]

I'd rather name that file "style-mutators" rather than "styling", so the purpose is explicit

[GuillaumeDua]

toggle_small -> toggle_small_style

Right now, this function only works if toggle_style was called before.

An improvement here would be to add a simple if-then here, such as :

if (!is_stylished)
   toggle_style()

and modify toggle_style so when L7 it removes the classes, then it also reset sizes

L7 :

function (elements) {
        elements.removeClass(`${stylished_classname}`);
        if (is_small)
            toggle_small()
      }