minor comment change

programs/fileio.c

@@ -132,6 +132,9 @@ void FIO_setMemLimit(unsigned memLimit) { g_memLimit = memLimit; }
 /*-*************************************
 *  Functions
 ***************************************/
+/** FIO_openSrcFile() :
+ * condition : `dstFileName` must be non-NULL.
+ * @result : FILE* to `dstFileName`, or NULL if it fails */
 static FILE* FIO_openSrcFile(const char* srcFileName)
 {
     FILE* f;