my %hash = (
  'bob' => [ "section-a", "section-b" ],
  'jan' => [ "section-d" ]
);

# And to add another....
foreach (qw(section-f section-g)) {
  push(@{$hash{'paul'}}, $_);
}

foreach my $k (keys(%hash)) {
  print "$k => ", join(",", @{$hash{$k}}), "\n";
}