CairoCanvas, modified readme file

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@40599 4005530d-fff6-0310-9dd1-cebe43e6787f
CairoCanvas, fix images, from Julio Jiménez Borreguero

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@40600 4005530d-fff6-0310-9dd1-cebe43e6787f