Re: Documenting gpg-agent

[Richard Stallman]

    ! When using GnuPG the additional use of the gpg-agent (@pxref{Caching
    ! passphrase}) is highly recommended, as it provides the most secure way
    ! for input and caching of passphrases.  Please refer to the documentation
    ! of GnuPG for details on installation and usage.

This isn't sufficient, because

1. It should have an Info xref to the proper node in the other manual.
"Please refer to the documentation of GnuPG" is not sufficient.

2. Just an xref is not enough.  This needs to actually explain the
simple usage of gpg-agent.

3. If this is the preferred method, to avoid a security hole,
then we should remove or deprecate other methods.