Add Changelog For Halma v15.0

Author: CrazyMarvin

fastlane/metadata/android/en-US/changelogs/15.txt

@@ -0,0 +1,4 @@
+- Fixed bugs 🐛
+
+A huge thank you to all contributors and translators, especially Mujahid. 😘
+Please feel welcome to open issues on https://github.com/Crazy-Marvin/Halma and help with translations on https://hosted.weblate.org/engage/halma/. 🚀