This is a follow-up to legacy/trac#24679. * update the default weight in parse_dir_fallback_line() to 10.0 * update the man page to reflect the new default 10.0 gives us: * 0.5% clients bootstrapping off an authority when all fallbacks are up, * 2% when 25% are down (our replacement threshold) * 7% when 40% are down (our worst case scenario)