Use a single pool directive

As pointed out in abh#218 ntpd and chronyd default to using
4 servers per pool.

docs/ntppool/en/use.html

@@ -36,8 +36,9 @@ <h3 id="use">How do I use pool.ntp.org?</h3>
 	On some Linux distributions <a href="https://chrony.tuxfamily.org/"><code>chronyd</code></a>
 	has replaced <code>ntpd</code> as the default NTP client (and server). With respect
 	to the time source configuration it uses the same syntax as <code>ntpd</code>,
-	so you can use the example above. Usually, the shipped configuration comes with a
-	a sensible default using the distribution's vendor pool and doesn't need any adjusting at all.
+	so you can use the example above, leaving out the <code>tos maxclock</codecode> line.
+	Usually, the shipped configuration comes with a sensible default using the distribution's
+	vendor pool and doesn't need any adjusting at all.
 	For checking on the synchronization status, use <code>chronyc -n sources</code>.
 	The output is similar to <code>ntpq</code> including the asterisk designating
 	the current time source.

docs/ntppool/use/sample-pool-config.html

@@ -1,8 +1,5 @@
 <pre class="code">
-driftfile /var/lib/ntp/ntp.drift
-
 pool 2.pool.ntp.org iburst
-pool 3.pool.ntp.org iburst
-pool 0.pool.ntp.org iburst
-pool 1.pool.ntp.org iburst
+
+tos maxclock 5
 </pre>