IPv6 all-balls address

I have applied the attached patch which documents the all-balls IPv6
address.

--
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + It's impossible for everything to be true. +
diff --git a/doc/src/sgml/client-auth.sgml b/doc/src/sgml/client-auth.sgml
new file mode 100644
index a2c0494..c05805b
*** a/doc/src/sgml/client-auth.sgml
--- b/doc/src/sgml/client-auth.sgml
*************** hostnossl  <replaceable>database</replac
*** 241,247 ****
         <literal>172.20.143.89/32</literal> for a single host, or
         <literal>172.20.143.0/24</literal> for a small network, or
         <literal>10.6.0.0/16</literal> for a larger one.
!        <literal>0.0.0.0/0</literal> (<quote>all balls</>) represents all addresses.
         To specify a single host, use a CIDR mask of 32 for IPv4 or
         128 for IPv6.  In a network address, do not omit trailing zeroes.
        </para>
--- 241,249 ----
         <literal>172.20.143.89/32</literal> for a single host, or
         <literal>172.20.143.0/24</literal> for a small network, or
         <literal>10.6.0.0/16</literal> for a larger one.
!        <literal>0.0.0.0/0</literal> (<quote>all balls</>) represents all
!        IPv4 addresses, and <literal>::</literal> represents
!        all IPv6 addresses.
         To specify a single host, use a CIDR mask of 32 for IPv4 or
         128 for IPv6.  In a network address, do not omit trailing zeroes.
        </para>