Bug#203298: /usr/share/man/man8/apt-cache.8.gz: say what versions if not all

[Dan Jacobson <jidanni@jidanni.org>]

Package: apt
Version: 0.5.7
Severity: normal
File: /usr/share/man/man8/apt-cache.8.gz

Regarding
       --all-versions
              Print full records for all available versions. This is only applicable to  the
              show command.  Configuration Item: APT::Cache::AllVersions.

* mention the default is yes. Don't expect the user to guess this
  option is on by default, while all the others aren't.

* mention what version you will get with --no-all-versions, newest? oldest? etc.