update HISTORY

Author: katahiromz

HISTORY.md

@@ -21,7 +21,7 @@
     - 6 FPS became default.
     - Fixed the timing gap by timeBeginPeriod(1).
     - Added sounds to Record/Stop/Hung.
-- 2019.XX.YY ver.0.9.1
+- 2019.12.11 ver.0.9.1
     - Implemented plug-ins.
     - Added Take-a-shot feature.
     - Made the main window modeless.