[4.0] 56adaeb -b is redundant

[Per Buer]

commit 56adaeb29445c6be2cf8dc4fc53e8a5dca5825b3
Author: Per Buer <perbu at varnish-software.com>
Date:   Wed Feb 26 12:30:21 2014 +0100

    -b is redundant

diff --git a/doc/sphinx/users-guide/increasing-your-hitrate.rst b/doc/sphinx/users-guide/increasing-your-hitrate.rst
index 9d1dc67..431c0fc 100644
--- a/doc/sphinx/users-guide/increasing-your-hitrate.rst
+++ b/doc/sphinx/users-guide/increasing-your-hitrate.rst
@@ -23,8 +23,10 @@ Tool: varnishtop
 ~~~~~~~~~~~~~~~~
 
 You can use varnishtop to identify what URLs are hitting the backend
-the most. ``varnishtop -b -i txurl`` is an essential command. You can see
-some other examples of varnishtop usage in :ref:`users-guide-statistics`.
+the most. ``varnishtop -i txurl`` is an essential command, showing you
+the top txurl requests Varnish is sending towards the backend. You can
+see some other examples of varnishtop usage in
+:ref:`users-guide-statistics`.
 
 
 Tool: varnishlog