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>