Broken links in the environment description

The Ruby Rack protocol link is broken.
Instead:
http://rack.rubyforge.org/doc/files/SPEC.html
should use:
https://www.rubydoc.info/github/rack/rack/master/file/SPEC

JSGI link is broken (website jackjs.org is not working).
Instead:
http://jackjs.org/jsgi-spec.html
perhaps should use:
http://wiki.commonjs.org/wiki/JSGI
