Add Tails signing key to key page

We should add the Tails signing key fingerprint to this page: https://www.torproject.org/docs/signing-keys.html.en

This is the key: https://tails.boum.org/tails-signing.key

This would be the correct addition to the page:

pub   4096R/BE2CD9C1 2010-10-07 [expires: 2012-10-06]
      Key fingerprint = 0D24 B36A A9A2 A651 7878  7645 1202 821C BE2C D9C1
uid                  Tails developers (signing key) <tails@boum.org>
uid                  T(A)ILS developers (signing key) <amnesia@boum.org>