Clarify that dots in URL are replaced

The dots in all path components from the document root are replaced with underscores, not only in the basename.

Author: nobu

test/rdoc/test_rdoc_top_level.rb

@@ -157,6 +157,9 @@ def test_hash
 
  def test_http_url
  assert_equal 'prefix/path/top_level_rb.html', @top_level.http_url('prefix')
+
+ other_level = @store.add_file 'path.other/level.rb'
+ assert_equal 'prefix/path_other/level_rb.html', other_level.http_url('prefix')
  end
 
  def test_last_modified