Add architecture section to FDP landing page

[crtahlin]

From email thread, quoting:

an "fdp architecture" section

• maybe at the top of the main page, something like this - https://docs.fairos.fairdatasociety.org/assets/images/FairOS-dfs-Architecture-0155a58aaa543dff5b4738ed4ad8f5d2.png
• and clicking parts of the image can jump to the related section below in the same page

We should definitively describe the architecture of FDP and how it all ties together, with an image and some paragraphs tying it together.

I suggest Miro to be used for diagramming, as it allows for collaborative work, but any tool would do.

• make a diagram of FDP architecture
• describe architecture in text
• put both onto FDP landing landing page in a new section
• OPTIONAL make diagram clickable, leading to relevant sections

[crtahlin]

@nugaon could you tackle the diagram and description parts?