pgsql: Use SGML table to show backslash string escapes, rather than have

Log Message:
-----------
Use SGML table to show backslash string escapes, rather than have them
appear in a paragraph.

Andy Anderson

Modified Files:
--------------
pgsql/doc/src/sgml:
syntax.sgml (r1.122 -> r1.123)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/syntax.sgml?r1=1.122&r2=1.123)