Update CHANGELOG.md

Author: oleibman

CHANGELOG.md

@@ -25,7 +25,24 @@ and this project adheres to [Semantic Versioning](https://semver.org).
 
 ### Fixed
 
-- Nothing
+- Html Reader Preserve Unicode Whitespace. [Issue #1284](https://github.com/PHPOffice/PhpSpreadsheet/issues/1284) [PR #4106](https://github.com/PHPOffice/PhpSpreadsheet/pull/4106)
+- RATE Function Floating Point Number of Periods. [PR #4107](https://github.com/PHPOffice/PhpSpreadsheet/pull/4107)
+- Parameter Name Change Xlsx Writer Workbook. [Issue #4108](https://github.com/PHPOffice/PhpSpreadsheet/issues/4108) [PR #4111](https://github.com/PHPOffice/PhpSpreadsheet/pull/4111)
+- New Algorithm for TRUNC, ROUNDUP, ROUNDDOWN. [Issue #4113](https://github.com/PHPOffice/PhpSpreadsheet/issues/4113) [PR #4115](https://github.com/PHPOffice/PhpSpreadsheet/pull/4115)
+
+
+## 2024-07-29 - 2.2.1
+
+### Security Fix
+
+- Prevent XXE when loading files [PR #4119](https://github.com/PHPOffice/PhpSpreadsheet/pull/4119)
+
+### Fixed
+
+- Add Sheet may leave Active Sheet uninitialized. [Issue #4112](https://github.com/PHPOffice/PhpSpreadsheet/issues/4112) [PR #4114](https://github.com/PHPOffice/PhpSpreadsheet/pull/4114)
+- Reference to Defined Name Specifying Worksheet. [Issue #206](https://github.com/PHPOffice/PhpSpreadsheet/issues/296) [PR #4096](https://github.com/PHPOffice/PhpSpreadsheet/pull/4096)
+- Xls Reader Print/Show Gridlines. [Issue #912](https://github.com/PHPOffice/PhpSpreadsheet/issues/912) [PR #4098](https://github.com/PHPOffice/PhpSpreadsheet/pull/4098)
+- ODS Reader Allow Omission of Page Settings Tags. [Issue #4099](https://github.com/PHPOffice/PhpSpreadsheet/issues/4099) [PR #4101](https://github.com/PHPOffice/PhpSpreadsheet/pull/4101)
 
 ## 2024-07-24 - 2.2.0