Update system tests after help changes.

system/t03_help/MainHelpTest_gold

@@ -3,6 +3,13 @@ repositories, manage local repositories, filter them, merge,
 upgrade individual packages, take snapshots and publish them
 back as Debian repositories.
 
+aptly goal is to establish repeatiblity and controlled changes
+in package environment. aptly allows to fix set of packages in
+repository, so that package installation and upgrade becomes
+deterministic. At the same time aptly allows to perform controlled,
+fine-grained changes in repository contents to transition your
+package environment to new version.
+
 Options:
   -architectures="": list of architectures to consider during (comma-separated), default to all available
   -config="": location of configuration file (default locations are /etc/aptly.conf, ~/.aptly.conf)