Clarify the meaning of version in redirdev filters

The version attribute in redirdev filters refers to the revision
of the device, not the version of the USB protocol.

Explicitly state that this is not the USB protocol and remove references
to those round version numbers that resemble USB protocol versions.

https://bugzilla.redhat.com/show_bug.cgi?id=1177237
(cherry picked from commit 76a2a5ce)
Signed-off-by: NJán Tomko <jtomko@redhat.com>

docs/formatdomain.html.in

@@ -3195,7 +3195,7 @@
       <boot order='1'/>
     </redirdev>
     <redirfilter>
-      <usbdev class='0x08' vendor='0x1234' product='0xbeef' version='2.00' allow='yes'/>
+      <usbdev class='0x08' vendor='0x1234' product='0xbeef' version='2.56' allow='yes'/>
       <usbdev allow='no'/>
     </redirfilter>
   </devices>
@@ -3238,7 +3238,8 @@
         <code>class</code> attribute is the USB Class code, for example,
         0x08 represents mass storage devices. The USB device can be addressed by
         vendor / product id using the <code>vendor</code> and <code>product</code> attributes.
-        <code>version</code> is the bcdDevice value of USB device, such as 1.00, 1.10 and 2.00.
+        <code>version</code> is the device revision from the bcdDevice field (not
+        the version of the USB protocol).
         These four attributes are optional and <code>-1</code> can be used to allow
         any value for them. <code>allow</code> attribute is mandatory,
         'yes' means allow, 'no' for deny.