Chore: Updated 1.2.0 changelog

Author: kw-pr

docs/changes/1.2.0.md

@@ -10,6 +10,7 @@
 ## Bug fixes
 
 - Word2007 Reader: Fixed cast of spacing fixing [#729](https://github.com/PHPOffice/PHPPresentation/pull/729), [#796](https://github.com/PHPOffice/PHPPresentation/pull/796) in [#818](https://github.com/PHPOffice/PHPPresentation/pull/818)
+- Word2007 Writer: Fixed missing images [#829](https://github.com/PHPOffice/PHPPresentation/pull/829) by [@kw-pr](https://github.com/kw-pr)
 
 ## Miscellaneous