[1.9.x] Fixed a dead link in django/contrib/sitemaps/__init__.py.

class Sitemap(object):

    # This limit is defined by Google. See the index documentation at

    # http://sitemaps.org/protocol.php#index.

    # http://www.sitemaps.org/protocol.html#index.

    limit = 50000

    # If protocol is None, the URLs in the sitemap will use the protocol