Backport from trunk r56727:
Fix gb18030 codec's bug that doesn't map two-byte characters on
GB18030 extension in encoding. (bug reported by Bjorn Stabell)
diff --git a/Misc/NEWS b/Misc/NEWS
index 0b01eaf..3d5221c 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -26,6 +26,9 @@
 Library
 -------
 
+- GB18030 codec now can encode additional two-byte characters that
+  are missing in GBK.
+
 - Bug #1704793: Raise KeyError if unicodedata.lookup cannot
   represent the result in a single character.