class Ronn::Document

def sniff

is represented by nil and any element may be missing.
tuple of the form: [name, section, description], where missing information
Sniff the document header and extract basic document metadata. Return a 
def sniff
  html = Markdown.new(data[0, 512]).to_html
  heading, html = html.split("</h1>\n", 2)
  return [nil, nil, nil] if html.nil?
  case heading
  when /([\w_.\[\]~+=@:-]+)\s*\((\d\w*)\)\s*-+\s*(.*)/
    # name(section) -- description
    [$1, $2, $3]
  when /([\w_.\[\]~+=@:-]+)\s+-+\s+(.*)/
    # name -- description
    [$1, nil, $2]
  else
    # description
    [nil, nil, heading.sub('<h1>', '')]
  end
end