Log Message:
-----------
Minor editorializing.
Modified Files:
--------------
pgsql-server/doc/src/sgml/ref:
set_transaction.sgml (r1.20 -> r1.21)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/doc/src/sgml/ref/set_transaction.sgml.diff?r1=1.20&r2=1.21)