Mention missing final step in getting header order back

[jidanni]

We read

       keep_headers

       When using hashes,  keep the column names into the arrayref passed,  so
       all headers are available after the call in the original order.

       my $aoh = csv( in => "file.csv", keep_headers => \my @hdr );

OK, but then you need to mention how to get them back:

       csv( in => $aoh, headers => \@hdr, out => "out.csv" );

else they'll go down the drain!