Update CHANGELOG.md

CHANGELOG.md

@@ -27,6 +27,7 @@ You should also include the user name that made the change.
 - Client: use tabler-icons instead of fontawesome to better design @syuilo
 - Client: Add new gabber kick sounds (thanks for noizenecio)
 - Client: Compress non-animated PNG files @saschanaz
+- Client: Youtube window player @sim1222
 
 ### Bugfixes
 - Server: 引用内の文章がnyaizeされてしまう問題を修正 @kabo2468