add missing border color to example
add missing border color to example

secondary and dark. Light color is the same as the background.
IronSummitMedia/startbootstrap-sb-admin-2,BlackrockDigital/startbootstrap-sb-admin-2,tnir/startbootstrap-sb-admin-2,IronSummitMedia/startbootstrap-sb-admin-2,tnir/startbootstrap-sb-admin-2,BlackrockDigital/startbootstrap-sb-admin-2