pgsql: pg_upgrade: document possible pg_hba.conf options

pg_upgrade: document possible pg_hba.conf options
Previously, pg_upgrade docs recommended using .pgpass if using MD5
authentication to avoid being prompted for a password.  Turns out pg_ctl
never prompts for a password, so MD5 requires .pgpass --- document that.
Also recommend 'peer' for authentication too.
Backpatch back to 9.1.

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/886c05d8e8642572af25fee23f414bd31f2e7f3e

Modified Files
--------------
doc/src/sgml/pgupgrade.sgml |    8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)