boards/cc1352: remove broken HTML links and headings from doc
boards/cc1352: remove broken HTML links and headings from doc

ant9000/RIOT,jasonatran/RIOT,jasonatran/RIOT,kaspar030/RIOT,RIOT-OS/RIOT,ant9000/RIOT,RIOT-OS/RIOT,RIOT-OS/RIOT,kaspar030/RIOT,ant9000/RIOT,kaspar030/RIOT,ant9000/RIOT,jasonatran/RIOT,jasonatran/RIOT,RIOT-OS/RIOT,kaspar030/RIOT,jasonatran/RIOT,ant9000/RIOT,kaspar030/RIOT,RIOT-OS/RIOT