[PATCH] Documentation: usb: fix sphinx warning

[Antony Pavlov]

The patch fixes this sphinx warnings:

    barebox/Documentation/user/usb.rst:61: WARNING: Could not lex literal_block as "c". Highlighting skipped.

Signed-off-by: Antony Pavlov <antonynpavlov at gmail.com>
Cc: Robert P. J. Day <rpjday at crashcourse.ca>
---
 Documentation/user/usb.rst | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/Documentation/user/usb.rst b/Documentation/user/usb.rst
index 8602a8f..bbcb045 100644
--- a/Documentation/user/usb.rst
+++ b/Documentation/user/usb.rst
@@ -56,7 +56,9 @@ shall be provided to the host. For the possible ``flags`` see
 
 On the host side, the tool `dfu-util <http://dfu-util.gnumonks.org/>`_ can be used
 to update the partitions. It is available for most distributions and typically
-supports the following options::
+supports the following options:
+
+.. code-block:: none
 
   dfu-util -h
   Usage: dfu-util [options] ...
-- 
2.9.3