pgsql: A small pass of docs review and copy-editing.

Log Message:
-----------
A small pass of docs review and copy-editing.

Modified Files:
--------------
    pgsql/doc/src/sgml:
        array.sgml (r1.41 -> r1.42)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/array.sgml.diff?r1=1.41&r2=1.42)
        datatype.sgml (r1.151 -> r1.152)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/datatype.sgml.diff?r1=1.151&r2=1.152)
        ddl.sgml (r1.34 -> r1.35)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ddl.sgml.diff?r1=1.34&r2=1.35)
        dml.sgml (r1.8 -> r1.9)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/dml.sgml.diff?r1=1.8&r2=1.9)
        intro.sgml (r1.26 -> r1.27)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/intro.sgml.diff?r1=1.26&r2=1.27)
        postgres.sgml (r1.68 -> r1.69)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/postgres.sgml.diff?r1=1.68&r2=1.69)
        queries.sgml (r1.31 -> r1.32)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/queries.sgml.diff?r1=1.31&r2=1.32)
        rowtypes.sgml (r2.3 -> r2.4)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/rowtypes.sgml.diff?r1=2.3&r2=2.4)
        syntax.sgml (r1.98 -> r1.99)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/syntax.sgml.diff?r1=1.98&r2=1.99)