RN: footer styling

The Creative Commons license styling on the footer is ugly. This change
alters the HTML slightly and centers the text.

Signed-off-by: Lucas Dutra Nunes <ldnunes@ossystems.com.br>
RN: Updates from bitbake-metadata2doc.sh

Signed-off-by: Daiane Angolini <daiane.angolini@freescale.com>