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.
<para>
<command>pg_upgrade</> will connect to the old and new servers several times,
- so you might want to set authentication to <literal>trust</> in
- <filename>pg_hba.conf</>, or if using <literal>md5</> authentication,
- use a <filename>~/.pgpass</> file (see <xref linkend="libpq-pgpass">)
- to avoid being prompted repeatedly for a password.
+ so you might want to set authentication to <literal>trust</>
+ or <literal>peer</> in <filename>pg_hba.conf</>, or if using
+ <literal>md5</> authentication, use a <filename>~/.pgpass</> file
+ (see <xref linkend="libpq-pgpass">).
</para>
</step>