pgsql: Basic documentation for ROLEs.

Log Message:
-----------
Basic documentation for ROLEs. The user-manag chapter still needs to
be rewritten, but at least the reference pages are reasonably sane.

Modified Files:
--------------
pgsql/doc/src/sgml:
reference.sgml (r1.54 -> r1.55)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/reference.sgml.diff?r1=1.54&r2=1.55)
pgsql/doc/src/sgml/ref:
allfiles.sgml (r1.64 -> r1.65)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/allfiles.sgml.diff?r1=1.64&r2=1.65)
alter_group.sgml (r1.15 -> r1.16)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/alter_group.sgml.diff?r1=1.15&r2=1.16)
alter_user.sgml (r1.37 -> r1.38)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/alter_user.sgml.diff?r1=1.37&r2=1.38)
create_group.sgml (r1.15 -> r1.16)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/create_group.sgml.diff?r1=1.15&r2=1.16)
create_user.sgml (r1.36 -> r1.37)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/create_user.sgml.diff?r1=1.36&r2=1.37)
drop_group.sgml (r1.10 -> r1.11)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/drop_group.sgml.diff?r1=1.10&r2=1.11)
drop_user.sgml (r1.20 -> r1.21)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/drop_user.sgml.diff?r1=1.20&r2=1.21)
grant.sgml (r1.47 -> r1.48)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/grant.sgml.diff?r1=1.47&r2=1.48)
revoke.sgml (r1.33 -> r1.34)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/revoke.sgml.diff?r1=1.33&r2=1.34)
set_role.sgml (r1.1 -> r1.2)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/set_role.sgml.diff?r1=1.1&r2=1.2)
set_session_auth.sgml (r1.13 -> r1.14)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/set_session_auth.sgml.diff?r1=1.13&r2=1.14)

Added Files:
-----------
pgsql/doc/src/sgml/ref:
alter_role.sgml (r1.1)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/alter_role.sgml?rev=1.1&content-type=text/x-cvsweb-markup)
create_role.sgml (r1.1)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/create_role.sgml?rev=1.1&content-type=text/x-cvsweb-markup)
drop_role.sgml (r1.1)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/drop_role.sgml?rev=1.1&content-type=text/x-cvsweb-markup)