Add Smart Rollup as a type of account (#230)

* Add Smart Rollup as a type of account

* Remove this TODO

* They have a tree of commitments attached to them.

docs/architecture/accounts.md

@@ -2,15 +2,20 @@
 title: Accounts
 authors: "Tim McMackin"
 last_update:
-  date: 18 October 2023
+  date: 29 December 2023
 ---
 
-Tezos uses two types of accounts:
+Tezos uses these types of accounts:
 
-- Classic accounts (also known as _implicit accounts_) with an address, storing tez (ꜩ).
+- Classic accounts (also known as _implicit accounts_) store tez (ꜩ) and tickets.
 These accounts have addresses that start with "tz1", "tz2", "tz3" or "tz4."
 Any wallet application or the Octez command-line tool can create implicit accounts.
 
-- Smart contract accounts (also known as _originated accounts_) with an address, storing code and tez (ꜩ).
-Originated accounts have addresses that start with "KT1."
-Creating an originated account is part of the process of deploying a smart contract; see [Smart contracts](../smart-contracts).
+- Smart contract accounts (also known as _originated accounts_) store immutable code, mutable storage, tez (ꜩ), and tickets.
+Smart contracts have addresses that start with "KT1."
+See [Smart contracts](../smart-contracts).
+
+- Smart Rollup accounts are another type of originated account.
+Their addresses start with `SR1`.
+They have a tree of commitments attached to them.
+See [Smart Optimistic Rollups](./smart-rollups).