Instructions add *all* PGP public keys to APT

[Ansgar Burchardt <ansgar@mathi.uni-heidelberg.de>]

Hi,

The instructions page says:

    gpg --keyserver hkp://subkeys.pgp.net --recv-keys 16BA136C
    gpg --export | apt-key add -

This will add *all* public keys to APT.  The second line should be replaced
with

    gpg --export 16BA136C | apt-key add -

to only add the key used by backports.org.

Regards,
Ansgar