Add release notes for v0.5.2
# Release Notes
+## Changes in Sawtooth Sabre 0.5.2
+
+* Add `Result` class to the AssemblyScript SDK for basic error handling
+* Update inc-dec example AssemblyScript smart contract to use `Result` for
+ errors
+* Fix bug where the Rust SDK was computing addresses with incorrect lengths
+* Add address prefixes and the administrators setting address as bytes constants
+ to the Rust SDK
+* Fix a bug where the administrators setting address was being converted to
+ bytes incorrectly
+* Add the Sabre protocol version to the Rust SDK as a constant to ensure the SDK
+ builds transactions for the equivalent version of the Sabre transaction
+ processor
+* Fix bug where the agent address was calculated incorrectly by the
+ `SabrePayloadBuilder::into_transaction_builder` method
+
## Changes in Sawtooth Sabre 0.5.1
* Update the family version for Sabre transactions in the Sabre transaction
