Add changelog entry

Author: Joy-less

CHANGELOG.md

@@ -6,6 +6,10 @@ All notable changes to **ValueStringBuilder** will be documented in this file. T
 
 ## [Unreleased]
 
+### Changed
+
+- Added performance short-circuit when span is empty in `Append(ReadOnlySpan<char>)`, `AppendSpan(int)`, `Insert(int, ReadOnlySpan<char>)` in #233 (by @Joy-less)
+
 ## [2.2.0] - 2025-01-25
 
 ### Added