Adding OpenShift Platform

[ravindk89]

Summary

This pull adds back the OpenShift docs as a full dedicated platform

The main changes are:

• Adding the conditionals for OpenShift
• Modifying the Makefile for the new platform
• Adding the tutorials back in
• Fixing up the navigation headers

This was not too much trouble, which bodes well for the future.

[ravindk89]

Closes #576

[djwfyi]

To do:

• [x] update build-docs.sh
• [ ] add sitemap to sitemap_index at min.io root
• [ ] update the Algolia crawler to add the sitemap and paths
• [ ] once published, restart the Algolia crawler to index it

[ravindk89]

build-docs updated - going to do a little more validation.

I am going to meet with @cniackz next week to go over OpenShift installation methods and validate that everything still works as expected. Once we get through that, we can publish these docs up.

[ravindk89]

@cniackz @druid-matt this should be about as good as it needs to be for the MVP1.0, based on Cesar's findings. Staged view is in minio-docs.