docs(changelog): Add note about supporting vAlign and vMerge to be unset

Author: SpraxDev

docs/changes/1.x/1.4.0.md

@@ -10,6 +10,7 @@
 ### Bug fixes
 
 - Writer ODText: Support for images inside a textRun by [@Progi1984](https://github.com/Progi1984) fixing [#2240](https://github.com/PHPOffice/PHPWord/issues/2240) in [#2668](https://github.com/PHPOffice/PHPWord/pull/2668)
+- Allow vAlign and vMerge on Style\Cell to be set to null by [@SpraxDev](https://github.com/SpraxDev) fixing [#2673](https://github.com/PHPOffice/PHPWord/issues/2673) in [#2676](https://github.com/PHPOffice/PHPWord/pull/2676)
 
 ### Miscellaneous