re-exposes CBORCoder and associated documentation

Sources/AutomergeRepo/Documentation.docc/Curation/CBORCoder.md

@@ -0,0 +1,11 @@
+# ``AutomergeRepo/CBORCoder``
+
+## Topics
+
+### Accessing a CBOR encoder
+
+- ``CBORCoder/encoder``
+
+### Accessing a CBOR decoder
+
+- ``CBORCoder/decoder``

Sources/AutomergeRepo/Documentation.docc/Documentation.md

@@ -58,6 +58,7 @@ The peer-to-peer provider uses of Apple's Bonjour technology to connect to other
 - ``AutomergeRepo/PEER_ID``
 - ``AutomergeRepo/STORAGE_ID``
 - ``AutomergeRepo/SYNC_MESSAGE``
+- ``CBORCoder``
 
 ### Share Policy
 

Sources/AutomergeRepo/Sync/CBORCoder.swift

@@ -1,8 +1,10 @@
 import Foundation
 import PotentCBOR
 
-/// A type that provides concurrency-safe access to the CBOR encoder and decoder.
-actor CBORCoder {
+/// A type that provides concurrency-safe access to a CBOR encoder and decoder.
+public actor CBORCoder {
+    /// A CBOR encoder
     public static let encoder = CBOREncoder()
+    /// A CBOR decoder
     public static let decoder = CBORDecoder()
 }