Add original author information (For code signing certificate).

PCMan · PCMan · commit def827c5cadb · 2021-11-30T22:13:10.000+08:00
diff --git a/LICENSE.txt b/LICENSE.txt
@@ -1,5 +1,7 @@
 PIME is composed of several parts with different licenses.
 
+Original author: Hong Jen-Yee <pcman.tw@gmail.com>
+
 Code in these directories are licensed under LGPL 2.0:
   cmake
   installer
