Add a "quick start" example section right below the options summary.

ndiff/docs/ndiff.xml

@@ -107,6 +107,57 @@
     </para>
   </refsect1>
 
+  <refsect1>
+    <title>Example</title>
+
+    <para>
+    Let's use Ndiff to compare the output of two Nmap scans that use
+    different options. In the first, we'll do a fast scan
+    (<option>-F</option>), which scans fewer ports for speed. In the
+    second, we'll scan the larger default set of ports, and run an NSE
+    script.
+    </para>
+
+<screen>
+# nmap -F scanme.nmap.org -oX scanme-1.xml
+# nmap --script=html-title scanme.nmap.org -oX scanme-2.xml
+$ ndiff -v scanme-1.xml scanme-2.xml
+-Nmap 4.90RC2 at 2009-07-16 13:29
++Nmap 4.90RC2 at 2009-07-16 13:33
+
+ scanme.nmap.org (64.13.134.52):
+ Host is up.
+-Not shown: 95 filtered ports
++Not shown: 993 filtered ports
+ PORT      STATE  SERVICE VERSION
+ 22/tcp    open   ssh
+ 25/tcp    closed smtp
+ 53/tcp    open   domain
++70/tcp    closed gopher
+ 80/tcp    open   http
++|_ html-title: Go ahead and ScanMe!
+ 113/tcp   closed auth
++31337/tcp closed Elite
+</screen>
+
+    <para>
+    Changes are marked by a <literal>-</literal> or <literal>+</literal>
+    at the beginning of a line. We can see from the output that the scan
+    without the <option>-F</option> fast scan option found two
+    additional ports: 70 and 31337. The
+    <filename>html-title.nse</filename> script produced some additional
+    output for port 80. From the port counts, we may infer that the fast
+    scan scanned 100 ports (95 filtered, 3 open, and 2 closed), while
+    the normal scan scanned 1000 (993 filtered, 3 open, and 4 closed).
+    </para>
+
+    <para>
+    The <option>-v</option> (or <option>--verbose</option>) option to
+    Ndiff made it show even the ports that didn't change, like 22 and
+    25. Without <option>-v</option>, they would not have been shown.
+    </para>
+  </refsect1>
+
   <refsect1>
     <title>Output</title>
 
@@ -164,7 +215,7 @@
   </refsect1>
 
   <refsect1>
-    <title>Example</title>
+    <title>Periodic Diffs</title>
 
     <para>
     Using Nmap, Ndiff, cron, and a shell script, it's possible to scan a