gss: add missing references to hostgssenc and hostnogssenc

These were missed when these were added to pg_hba.conf in PG 12;
updates docs and pg_hba.conf.sample.

Reported-by: Arthur Nascimento

Bug: 16380

Discussion: https://postgr.es/m/20200421182736.GG19613@momjian.us

Backpatch-through: 12

doc/src/sgml/client-auth.sgml

@@ -99,12 +99,14 @@
   </para>
 
   <para>
-   A record can have one of the seven formats
+   A record can have several formats:
 <synopsis>
 local         <replaceable>database</replaceable>  <replaceable>user</replaceable>  <replaceable>auth-method</replaceable> <optional><replaceable>auth-options</replaceable></optional>
 host          <replaceable>database</replaceable>  <replaceable>user</replaceable>  <replaceable>address</replaceable>     <replaceable>auth-method</replaceable>  <optional><replaceable>auth-options</replaceable></optional>
 hostssl       <replaceable>database</replaceable>  <replaceable>user</replaceable>  <replaceable>address</replaceable>     <replaceable>auth-method</replaceable>  <optional><replaceable>auth-options</replaceable></optional>
 hostnossl     <replaceable>database</replaceable>  <replaceable>user</replaceable>  <replaceable>address</replaceable>     <replaceable>auth-method</replaceable>  <optional><replaceable>auth-options</replaceable></optional>
+hostgssenc    <replaceable>database</replaceable>  <replaceable>user</replaceable>  <replaceable>address</replaceable>     <replaceable>auth-method</replaceable>  <optional><replaceable>auth-options</replaceable></optional>
+hostnogssenc  <replaceable>database</replaceable>  <replaceable>user</replaceable>  <replaceable>address</replaceable>     <replaceable>auth-method</replaceable>  <optional><replaceable>auth-options</replaceable></optional>
 host          <replaceable>database</replaceable>  <replaceable>user</replaceable>  <replaceable>IP-address</replaceable>  <replaceable>IP-mask</replaceable>      <replaceable>auth-method</replaceable>  <optional><replaceable>auth-options</replaceable></optional>
 hostssl       <replaceable>database</replaceable>  <replaceable>user</replaceable>  <replaceable>IP-address</replaceable>  <replaceable>IP-mask</replaceable>      <replaceable>auth-method</replaceable>  <optional><replaceable>auth-options</replaceable></optional>
 hostnossl     <replaceable>database</replaceable>  <replaceable>user</replaceable>  <replaceable>IP-address</replaceable>  <replaceable>IP-mask</replaceable>      <replaceable>auth-method</replaceable>  <optional><replaceable>auth-options</replaceable></optional>
@@ -356,8 +358,7 @@ hostnogssenc <replaceable>database</replaceable>  <replaceable>user</replaceable
       </para>
 
       <para>
-       This field only applies to <literal>host</literal>,
-       <literal>hostssl</literal>, and <literal>hostnossl</literal> records.
+       These fields do not apply to <literal>local</literal> records.
       </para>
 
       <note>
@@ -409,8 +410,7 @@ hostnogssenc <replaceable>database</replaceable>  <replaceable>user</replaceable
       </para>
 
       <para>
-       These fields only apply to <literal>host</literal>,
-       <literal>hostssl</literal>, and <literal>hostnossl</literal> records.
+       These fields do not apply to <literal>local</literal> records.
       </para>
      </listitem>
     </varlistentry>

src/backend/libpq/pg_hba.conf.sample

@@ -13,13 +13,17 @@
 # host          DATABASE  USER  ADDRESS  METHOD  [OPTIONS]
 # hostssl       DATABASE  USER  ADDRESS  METHOD  [OPTIONS]
 # hostnossl     DATABASE  USER  ADDRESS  METHOD  [OPTIONS]
+# hostgssenc    DATABASE  USER  ADDRESS  METHOD  [OPTIONS]
+# hostnogssenc  DATABASE  USER  ADDRESS  METHOD  [OPTIONS]
 #
 # (The uppercase items must be replaced by actual values.)
 #
 # The first field is the connection type: "local" is a Unix-domain
 # socket, "host" is either a plain or SSL-encrypted TCP/IP socket,
 # "hostssl" is an SSL-encrypted TCP/IP socket, and "hostnossl" is a
-# plain TCP/IP socket.
+# non-SSL TCP/IP socket.  Similarly, "hostgssenc" uses a
+# GSSAPI-encrypted TCP/IP socket, while "hostnogssenc" uses a
+# non-GSSAPI socket.
 #
 # DATABASE can be "all", "sameuser", "samerole", "replication", a
 # database name, or a comma-separated list thereof. The "all"