Fix Documentation links pointing to github.io

[tiwillia]

Documentation links previously pointing to openshift.github.io are
broken and must be changed to point to the corresponding adoc file in
the github origin-server repository.

Any links to documentation not provided in the origin-server repository
(such as the api guide) have been changed to point to the publicly
available enterprise documentation.

Fixes issue #6401

[tiwillia]

There are still several places where openshift.github.io is referred to, but I beleive these can be ignored. They are only there to be used during generation of documentation, which will no longer be done:

documentation/templates/document.html.haml:          %a(href='http://openshift.github.io')
documentation/Rakefile:    hangouts.concat([description, "", '++++', "<iframe id='ytplayer' type='text/html' width='640' height='390' src='http://www.youtube.com/embed/#{video_id}?autoplay=0&origin=http://openshift.github.io' frameborder='0' allowfullscreen></iframe>", '++++', ""])
documentation/oo_troubleshooting_guide.adoc:* OpenShift Origin Home: http://openshift.github.io/
documentation/README.md:When the documentation is deployed to [openshift.github.io](http://openshift.github.io/documentation/), this build command:

[tiwillia]

@Miciah can you give this a look when you have a chance? There were many more affected files than expected.

[tiwillia]

@nhr fyi

[nhr]

This looks good. Thank you for running these down.

[tiwillia]

[merge] please!

[openshift-bot]

Online Merge Results: SUCCESS (https://ci.dev.openshift.redhat.com/jenkins/job/test_pull_requests/9338/) (Image: devenv_5805)

[openshift-bot]

Evaluated for online merge up to f70df8e