docs: add sample output to "standby follow" and "standby promote"

doc/repmgr-node-rejoin.sgml

@@ -14,6 +14,14 @@
      a standby to the current primary, not another standby.
    </simpara>
   </note>
+
+  <tip>
+    <para>
+      If the node is running and needs to be attached to the current primary, use
+      <xref linkend="repmgr-standby-follow">.
+    </para>
+  </tip>
+
   <para>
     This can optionally use <application>pg_rewind</application> to re-integrate a node which has diverged
     from the rest of the cluster, typically a failed primary.

doc/repmgr-standby-follow.sgml

@@ -11,11 +11,25 @@
   </para>
   <para>
    This command will force a restart of the standby server, which must be
-   running. It can only be used to attach a standby to a new primary node.
+   running. It can only be used to attach an active standby to the current primary node
+   (and not to another standby).
   </para>
   <para>
    To re-add an inactive node to the replication cluster, see
    <xref linkend="repmgr-node-rejoin">
   </para>
+  <para>
+    Example execution:
+    <programlisting>
+      $ repmgr -f /etc/repmgr.conf standby follow
+      INFO: setting node 3's primary to node 2
+      NOTICE: restarting server using "pg_ctl -l /var/log/postgres/startup.log -w -D '/var/lib/postgres/data' restart"
+      waiting for server to shut down........ done
+      server stopped
+      waiting for server to start.... done
+      server started
+      NOTICE: STANDBY FOLLOW successful
+      DETAIL: node 3 is now attached to node 2</programlisting>
+  </para>
 </chapter>
 

doc/repmgr-standby-promote.sgml

@@ -15,4 +15,16 @@
    by using <xref linkend="repmgr-standby-follow">; if <application>repmgrd</application>
    is active, it will handle this automatically.
   </para>
+  <para>
+    Example execution:
+    <programlisting>
+      $ repmgr -f /etc/repmgr.conf standby promote
+      NOTICE: promoting standby to primary
+      DETAIL: promoting server "node2" (ID: 2) using "pg_ctl -l /var/log/postgres/startup.log -w -D '/var/lib/postgres/data' promote"
+      server promoting
+      DEBUG: setting node 2 as primary and marking existing primary as failed
+      NOTICE: STANDBY PROMOTE successful
+      DETAIL: server "node2" (ID: 2) was successfully promoted to primary
+    </programlisting>
+  </para>
 </chapter>

doc/repmgrd-demonstration.sgml

@@ -61,7 +61,7 @@
     [2017-08-24 23:32:12] [NOTICE] this node is the winner, will now promote self and inform other nodes
     INFO: connecting to standby database
     NOTICE: promoting standby
-    DETAIL: promoting server using '/home/barwick/devel/builds/HEAD/bin/pg_ctl -l /tmp/postgres.5602.log -w -D '/tmp/repmgr-test/node_2/data' promote'
+    DETAIL: promoting server using '/home/barwick/devel/builds/HEAD/bin/pg_ctl -l /var/log/postgres/startup.log -w -D '/tmp/repmgr-test/node_2/data' promote'
     INFO: reconnecting to promoted server
     NOTICE: STANDBY PROMOTE successful
     DETAIL: node 2 was successfully promoted to primary