my @new_line_strings = (
   'Heading Here',
   );
my @opening_strings = (
   'Heading Here',
   'Another Heading',
   );
my @closing_strings = (
   'End of section',
   @opening_strings,
   );

my $new_line_pattern = '^(?:' . join('|', @new_line_strings) . ')';
my $opening_pattern = '^(?:' .  join('|', @opening_strings) . ')';
my $closing_pattern = '^(?:' .  join('|', @closing_strings) . ')';
   
while ( defined (my $line = <DATA> ) )
{
   state $indent_char = '';
   $indent_char = '' if $line =~ m/$closing_pattern/;
   print "\n" if $line =~ m/$new_line_pattern/;
   print $indent_char . $line;
   $indent_char = '  ' if $line =~ m/$opening_pattern/;
}