Create how-sui-works.md (MystenLabs#695)

Move Architecture section from SUI README to dedicated page

doc/src/learn/how-sui-works.md

@@ -0,0 +1,28 @@
+---
+title: How Sui Works
+---
+
+Sui is a distributed ledger that stores a collection of programmable *[objects](https://github.com/MystenLabs/fastnft/tree/main/doc/src/objects.md)*, each with a globally unique ID. Every object is owned by a single *address*, and each address can own an arbitrary number of objects.
+
+The ledger is updated via a *[transaction](https://github.com/MystenLabs/fastnft/tree/main/doc/src/transactions.md)* sent by a particular address. A transaction can create, destroy, and write objects, as well as transfer them to other addresses.
+
+Structurally, a transaction contains a set of input object references and a pointer to a Move code object that already exists in the ledger. Executing a transaction produces updates to the input objects and (if applicable) a set of freshly created objects along with their owners. A transaction whose sender is address *A* can accept objects owned by *A*, shared objects, and objects owned by other objects in the first two groups as input.
+
+```mermaid
+flowchart LR
+    CC(CLI Client) --> ClientService
+    RC(Rest Client) --> ClientService
+    RPCC(RPC Client) --> ClientService
+    ClientService --> AuthorityAggregator
+    AuthorityAggregator --> AC1[AuthorityClient] & AC2[AuthorityClient]
+    subgraph Authority1
+      AS[AuthorityState]
+    end
+    subgraph Authority2
+      AS2[AuthorityState]
+    end
+    AC1 <==>|Network TCP| Authority1
+    AC2 <==>|Network TCP| Authority2
+```
+
+Sui authorities agree on and execute transactions in parallel with high throughput using [Byzantine Consistent Broadcast](https://en.wikipedia.org/wiki/Byzantine_fault).