This update is basically to 'remove' the option of using Credit Cards on eShop when located in EU or UK.
Due to new privacy laws in EU, starting in September, systems which are not 100% secured to latest security standards for Credit Cards, like for example the 3DS or Wii U, can no longer be allowed to use them directly online, if you wish to purchase eShop items now via CC, you will have to do so online via a PC linked to your Nintendo Account.
Due to new privacy laws in EU, starting in September, systems which are not 100% secured to latest security standards for Credit Cards, like for example the 3DS or Wii U, can no longer be allowed to use them directly online, if you wish to purchase eShop items now via CC, you will have to do so online via a PC linked to your Nintendo Account.