Doc optimization for GSC and mobile viewers

[OlufunkeMoronfolu]

Here is what to expect with this PR:

• Fixed the long-standing mobile unresponsiveness. Now, when on small screens, users can see the hamburger menu, which opens the sidebar when clicked. Test by minimizing your screen.
• The doc content is now reordered to enable better crawling and should solve our crawling problem with Google. Test this by using either the browser's:
  • View page source
  • Inspect

[MarkvanMents]

Hi @OlufunkeMoronfolu
This looks great.
Haven't been able to fully review the code, but can't see any issues when I test it.
Let's get it out there and check that Google is happy indexing the restructured page.
Thanks for much for picking this up.
Mark