C++: Add changenote

Author: andersfugmann

cpp/change-notes/2021-09-13-overflow-static.md

@@ -0,0 +1,6 @@
+lgtm,codescanning
+* The `Buffer` library considers more fields to be of variable size
+  for array members of size 0 or 1. Buffer size calculation of array type
+  fields of size 0 or 1 in unions are considered pointers to the union
+  and will return the size of the union itself. The changes reduces
+  the number of false positives in cpp/static-buffer-overflow