Add diagrams to pdf

[williamdemeo]

We need high-level diagrams that illustrate the overall layout of the ledger and how it works as a state machine (and as a ledger).

The new diagrams should go in cardano-ledger.pdf (probably not in conway-ledger.pdf which is mainly for describing aspects of the ledger that are specific to Conway).

Probably we want to start off with something simple, like the tikz latex package. However, automating the generation of diagrams would enable us to make sure the diagrams are updated when changes to the ledger occur. This will make the formal spec easier to maintain and help ensure the diagrams are correct and not misleading readers.

For automation, we might try to use the diagrams language, since it is Haskell based so could probably be plugged right into our stack without too much effort. However, it may take a day or two to learn and figure out how to configure and integrate it.

[williamdemeo]

Existing Diagrams

• Figure 78 (STS Rules, Sub-rules and Dependencies) in shelley-ledger.pdf; the file rules.dot is used to generate Fig 78.
• Alexey's hand-drawn diagrams*
• Joosep's Haskell codebase diagram*

(* = links to internal Slack message or content)