describe script usage in the manpage

cmdline/apt.cc

@@ -107,17 +107,6 @@ int main(int argc, const char *argv[])					/*{{{*/
 
    std::vector<CommandLine::Args> Args = getCommandArgs("apt", CommandLine::GetCommand(Cmds, argc, argv));
 
-   if(!isatty(1)) 
-   {
-      std::cerr << std::endl
-                << "WARNING WARNING "
-                << argv[0]
-                << " is *NOT* intended for scripts "
-                << "use at your own peril^Wrisk"
-                << std::endl
-                << std::endl;
-   }
-
    InitOutput();
 
    // Set up gettext support

doc/apt.8.xml

@@ -124,7 +124,15 @@
    </variablelist>
  </refsect1>
 
-</refsect1>
+ <refsect1><title>Script usage</title>
+  <para>
+   The &apt; commandline is designed as a end-user tool and it may
+   change the output between versions. While it tries to not break
+   backward compatibility there is no guarantee for it either.
+   All features of &apt; are available in  &apt-cache; and &apt-get;
+   via APT options. Please prefer using these commands in your scripts.
+  </para>
+ </refsect1>
 
  <refsect1><title>Differences to &apt-get;</title>
  <para>The <command>apt</command> command is meant to be pleasant for