website: add cc2520 support entry

Signed-off-by: Varka Bhadram <varkab@cdac.in>
Signed-off-by: Alexander Aring <alex.aring@gmail.com>
website: change theme to 'volnitsky'

Signed-off-by: Varka Bhadram <varkab@cdac.in>
Signed-off-by: Alexander Aring <alex.aring@gmail.com>