RubySpec moved to ruby-doc subdomain

[Charles Oliver Nutter-2]

I've finally transferred the RubySpec wiki to a server hosted under the
ruby-doc "spec" subdomain.

http://spec.ruby-doc.org/wiki (spec.ruby-doc.org redirects here, since
in the future there may be other things we'd like to host under this domain)

Any links on the main ruby-doc site that are pointing at headius.com
should be updated to appropriate locations under the new address.
headius.com/rubyspec/* are all set to redirect to the spec.ruby-doc.org
site.

- Charlie