Fix a pdf doc build warning where a link wasn't recognised:
doc/guides/contributing/documentation.rst::
WARNING: unusable reference target found: inkscape.org
Signed-off-by: John McNamara <john.mcnamara@intel.com>
Acked-by: Harry van Haaren <harry.van.haaren@intel.com>
* The DPDK documentation contains some legacy images in PNG format.
These will be converted to SVG in time.
-* `Inkscape <inkscape.org>`_ is the recommended graphics editor for creating the images.
+* `Inkscape <http://inkscape.org>`_ is the recommended graphics editor for creating the images.
Use some of the older images in ``doc/guides/prog_guide/img/`` as a template, for example ``mbuf1.svg``
or ``ring-enqueue.svg``.