Obsolete links to security tokens

[viccie30]

The FAQ links to 3 tokens: https://github.com/open-keychain/open-keychain/blob/master/OpenKeychain%2Fsrc%2Fmain%2Fres%2Fraw%2Fhelp_faq.md#L68-L70

The Fidesmo Privacy Card does not seem to be available anymore. The Yubikey link redirects to a different model. The SIGILANCE link leads to an ad-filled domain parking page.