chore: add changelog entry

Author: kantai

CHANGELOG.md

@@ -5,6 +5,15 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to the versioning scheme outlined in the [README.md](README.md).
 
+## [Unreleased]
+
+### Added
+
+- The stacks-node miner now performs accurate tenure-extensions in certain bitcoin block production
+  cases: when a bitcoin block is produced before the previous bitcoin block's Stacks tenure started.
+  Previously, the miner had difficulty restarting their missed tenure and extending into the new
+  bitcoin block, leading to 1-2 bitcoin blocks of missed Stacks block production.
+
 ## [3.1.0.0.3]
 
 ### Added