Protocol participants diagram

[PaulRBerg]

• Inspiration: Maker Protocol 101
• Location: new section "Protocol Participants" in the Diagrams page
• Recommendation: do not use Mermaid.js because it doesn't have user silhouettes

[PaulRBerg]

Similarly, it would be helpful to have a diagram that shows a simple stream creation flow:

1. Alice deposits DAI in Sablier
2. DAI is streamed
3. Bob withdraws DAI after some time passes