Add a single receiver tx sequence diagram
//! illustrates the progression of the two state machines and shows where the public data messages are constructed and
//! accepted in each state machine
//!
+//! The sequence diagram for the single receiver protocol is:
+//!
+//! <div class="mermaid">
+//! sequenceDiagram
+//! participant Sender
+//! participant Receiver
+//! #
+//! activate Sender
+//! Sender-->>Sender: initialize transaction
+//! deactivate Sender
+//! #
+//! activate Sender
+//! Sender-->>+Receiver: partial tx info
+//! Receiver-->>Receiver: validate tx info
+//! Receiver-->>Receiver: create new output and sign
+//! Receiver-->>-Sender: signed partial transaction
+//! deactivate Sender
+//! #
+//! activate Sender
+//! Sender-->>Sender: validate and sign
+//! deactivate Sender
+//! #
+//! alt tx is valid
+//! Sender-->>Network: Broadcast transaction
+//! else tx is invalid
+//! Sender--XSender: Failed
+//! end
+//! </div>
+//!
+//! If there are multiple recipients, the protocol is more involved and requires three rounds of communication:
+//!
//! <div class="mermaid">
//! sequenceDiagram
//! participant Sender
