MdeModulePkg:Refine the code comments in UiApp

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Dandan Bi <dandan.bi@intel.com>
Reviewed-by: Eric Dong <eric.dong@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18151 6f19259b-4bc3-4df7-8a09-765794883524

MdeModulePkg/Application/UiApp/String.c

@@ -40,6 +40,10 @@ InitializeStringSupport (
   ASSERT (gStringPackHandle != NULL);
 }
 
+/**
+  Remove the string package.
+
+**/
 VOID
 UninitializeStringSupport (
   VOID