Docs: updates changelog

Author: mindline-analytics

docs/changes/1.2.0.md

@@ -10,6 +10,9 @@
 - `phpoffice/phpspreadsheet`: Allow version 3.0 by [@Progi1984](https://github.com/Progi1984) fixing [#836](https://github.com/PHPOffice/PHPPresentation/pull/836) in [#839](https://github.com/PHPOffice/PHPPresentation/pull/839)
 - `createAutoShape` : Add method to create geometric shapes by [@mhasanshahid](https://github.com/mhasanshahid) & [@Progi1984](https://github.com/Progi1984) in [#848](https://github.com/PHPOffice/PHPPresentation/pull/848)
 - Reader : Option to not load images by [@Progi1984](https://github.com/Progi1984) fixing [#795](https://github.com/PHPOffice/PHPPresentation/pull/795) in [#850](https://github.com/PHPOffice/PHPPresentation/pull/850)
+- PowerPoint2007 Writer : Improve series data labels - [@mindline](https://github.com/mindline-analytics) GH-709
+    - adds data labels number format for all chart types
+    - skips data labels xml if no lables should be shown 
 
 ## Bug fixes