doc: update quickstart guide

Improve sample PostgreSQL replication configuration, including
links to the PostgreSQL documentation for each configuration item.

Also set "max_replication_slots" to the same value as "max_wal_senders"
to ensure the sample configuration will work regardless of whether
replication slots are in use, though we do still encourage careful
reading of the comments in the sample configuration and the documentation
in general.

doc/quickstart.sgml

@@ -76,19 +76,25 @@
    </para>
    <programlisting>
 
-    # Enable replication connections; set this figure to at least one more
+    # Enable replication connections; set this value to at least one more
     # than the number of standbys which will connect to this server
-    # (note that repmgr will execute `pg_basebackup` in WAL streaming mode,
+    # (note that repmgr will execute "pg_basebackup" in WAL streaming mode,
-    # which requires two free WAL senders)
+    # which requires two free WAL senders).
+    #
+    # See: https://www.postgresql.org/docs/current/runtime-config-replication.html#GUC-MAX-WAL-SENDERS
 
     max_wal_senders = 10
 
-    # Enable replication slots; set this figure to at least one more
+    # If using replication slots, set this value to at least one more
     # than the number of standbys which will connect to this server.
     # Note that repmgr will only make use of replication slots if
-    # "use_replication_slots" is set to "true" in repmgr.conf
+    # "use_replication_slots" is set to "true" in "repmgr.conf".
+    # (If you are not intending to use replication slots, this value
+    # can be set to "0").
+    #
+    # See: https://www.postgresql.org/docs/current/runtime-config-replication.html#GUC-MAX-REPLICATION-SLOTS
 
-    max_replication_slots = 0
+    max_replication_slots = 10
 
     # Ensure WAL files contain enough information to enable read-only queries
     # on the standby.
@@ -103,24 +109,31 @@
 
     # Enable read-only queries on a standby
     # (Note: this will be ignored on a primary but we recommend including
-    # it anyway)
+    # it anyway, in case the primary later becomes a standby)
+    #
+    # See: https://www.postgresql.org/docs/current/runtime-config-replication.html#GUC-HOT-STANDBY
 
     hot_standby = on
 
     # Enable WAL file archiving
+    #
+    # See: https://www.postgresql.org/docs/current/runtime-config-wal.html#GUC-ARCHIVE-MODE
+
     archive_mode = on
 
-    # Set archive command to a script or application that will safely store
+    # Set archive command to a dummy command; this can later be changed without
-    # you WALs in a secure place. /bin/true is an example of a command that
+    # needing to restart the PostgreSQL instance.
-    # ignores archiving. Use something more sensible.
+    #
+    # See: https://www.postgresql.org/docs/current/runtime-config-wal.html#GUC-ARCHIVE-COMMAND
+
     archive_command = '/bin/true'
    </programlisting>
    <tip>
     <simpara>
       Rather than editing these settings in the default <filename>postgresql.conf</filename>
-     file, create a separate file such as <filename>postgresql.replication.conf</filename> and
+      file, create a separate file such as <filename>postgresql.replication.conf</filename> and
       include it from the end of the main configuration file with:
-     <command>include 'postgresql.replication.conf</command>.
+     <command>include 'postgresql.replication.conf'</command>.
     </simpara>
    </tip>
    <para>
@@ -129,7 +142,8 @@
      <varname>wal_log_hints</varname>; for more details see <xref linkend="repmgr-node-rejoin-pg-rewind">.
    </para>
     <para>
-      See also the <link linkend="configuration-postgresql">PostgreSQL configuration</link> section in the <link linkend="configuration">repmgr configuaration guide</link>.
+      See also the <link linkend="configuration-postgresql">PostgreSQL configuration</link> section in the
+      <link linkend="configuration">repmgr configuration guide</link>.
     </para>
  </sect1>