merge documentation fix

Hi,

While inspecting the MERGE documentation, I noticed that there is an extra
semicolon in one of the examples that shouldn't be there.

diff --git a/doc/src/sgml/ref/merge.sgml b/doc/src/sgml/ref/merge.sgml
index c547122c9b..ac1c0a83dd 100644
--- a/doc/src/sgml/ref/merge.sgml
+++ b/doc/src/sgml/ref/merge.sgml
@@ -596,7 +596,7 @@ ON s.winename = w.winename
WHEN NOT MATCHED AND s.stock_delta > 0 THEN
   INSERT VALUES(s.winename, s.stock_delta)
WHEN MATCHED AND w.stock + s.stock_delta > 0 THEN
-  UPDATE SET stock = w.stock + s.stock_delta;
+  UPDATE SET stock = w.stock + s.stock_delta
WHEN MATCHED THEN
   DELETE;
</programlisting>

--
Euler Taveira
EDB https://www.enterprisedb.com/