Update bonding HOWTO link (#421)

bsc#1231633
jsc#DOCTEAM-1618

xml/ha_netbonding.xml

@@ -366,22 +366,15 @@
 
   <para>
    All modes and many options are explained in detail in the
-   <guimenu>Linux Ethernet Bonding Driver HOWTO</guimenu>. The file can be
-   found at
-   <filename>/usr/src/linux/Documentation/networking/bonding.txt</filename>
-   after you have installed the package
-   <systemitem>kernel-source</systemitem>.
+   <guimenu>Linux Ethernet Bonding Driver HOWTO</guimenu>
+   at <link xlink:href="https://www.kernel.org/doc/Documentation/networking/bonding.txt"/>.
   </para>
 
   <para>
-   For &ha; setups, the following options described therein are
+   For &ha; setups, the following options are
    especially important: <option>miimon</option> and
    <option>use_carrier</option>.
   </para>
 
-<!--
-  http://www.cyberciti.biz/howto/question/static/linux-ethernet-bonding-driver-howto.php
-  - this is not as fresh as the Kernel documentation!
--->
  </sect1>
 </chapter>