```ruby
require 'colorize'

module HHVM
  module UserDocumentation
    class IncludeExamplesFilter < HTML::Pipeline::Filter
      def call
        base = File.dirname(context[:file])
        doc.search('p').each do |node|
          contents = node.inner_text.strip
          if match_data = /^@@ (?<relative_path>[^ ]+\.php(?:.type-errors)?) @@$/.match(contents)
            relative_path = match_data['relative_path']
            full_path = File.expand_path(relative_path, base)

            if ! File.exists? full_path
              text = "Missing example: #{full_path}"
              STDERR.write(
                text.red.bold + "\n"
              )
              warning = doc.document.create_element(
                'h1',
                text,
                style: 'color: red',
              )
              node.replace(warning)
              next
            end

            code = doc.document.create_element(
              'pre',
              File.read(full_path),
              language: 'Hack',
            );
            node.replace(code)
          end
        end
        doc
      end
    end
  end
end
```

Update markdown renderer to support new layout
user
```ruby
require 'colorize'

module HHVM
  module UserDocumentation
    class IncludeExamplesFilter < HTML::Pipeline::Filter
      def call
        file = context[:file]

        # Actual directory is something like 01-foo-examples/ ...
        examples_dir = File.basename(file, '.md') + '-examples'
        # ... but to make reordering easier, the references to it in the
        # markdown skip the '01-' prefix.
        match = /^[0-9]+-(?<source_dir>.+)/.match(examples_dir)
        return(doc) if match.nil?
        source_examples_dir = match['source_dir']

        base = File.expand_path(examples_dir, File.dirname(file))

        doc.search('p').each do |node|
          contents = node.inner_text.strip
          if match = %r,^@@ (?<dir_name>[^/ ]+)/(?<file_name>[^/ ]+\.php(?:.type-errors)?) @@$,.match(contents)
            next if match[:dir_name] != source_examples_dir

            full_path = File.expand_path(match[:file_name], base)

            if ! File.exists? full_path
              text = "Missing example: #{full_path}"
              STDERR.write(
                text.red.bold + "\n"
              )
              warning = doc.document.create_element(
                'h1',
                text,
                style: 'color: red',
              )
              node.replace(warning)
              next
            end

            code = doc.document.create_element(
              'pre',
              File.read(full_path),
              language: 'Hack',
            );
            node.replace(code)
          end
        end
        doc
      end
    end
  end
end
```
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