-- Performs the following transformations on Link targets:
--
--     Case 1:
--         [text](/chapter/#more-stuff) -> [text](#chapter-more-stuff)
--
--     Case 2:
--         [text](/chapter/)            -> [text](#chapter)
--
-- All other Links are ignored.
function Link (el)
  local n
  -- Case 1:
  el.target, n = el.target:gsub("^/(%w+)/#([%w-]+)$", "#%1-%2")
  -- Case 2:
  if n == 0 then
    el.target = el.target:gsub("^/(%w+)/$", "#%1")
  end
  return el
end