Slides on DID-related work

Christopher mentioned he was interested in DID-related presentations for
the Wyoming blockchain laws.

Attached is a presentation I used last week at a session
<https://www.kuppingercole.com/sessions/2312> at the European Identity &
Cloud Conference.

It's basically a single diagram of DID-related standardization and other
work, including
- historical background (left)
- current developments (middle)
- associated activities (right)
- dependencies (bottom)
- building on top (top)

If it's useful to anyone, feel free to do whatever you like with it
(cut&paste, re-brand, etc.).
Also curious if anything significant is missing or wrong.

Markus