Change-Id: Ia22f286e85be90983ca79291b3a54596bba30d6c

We have agreed to remove support for Oracle Linux.

http://lists.openstack.org/pipermail/openstack-discuss/2019-June/006896.html

Change-Id: If11b4ff37af936a0cfd34443e8babb952307882b

This ensures we have version-specific references to other projects [1].
Note that this doesn't mean the URLs are actually valid - we need to do
more work (linkcheck?) here, but it's an improvement nonetheless.

[1] https://docs.openstack.org/openstackdocstheme/latest/#external-link-helper

Change-Id: I118e4d211617c5df66ff04dc04e308a1d2fc67ad

Change index to ease identify what service want to look.
Split docs into more specific folder such as networking
and storage.

Change-Id: Ic7ac12b3dd555fa5c018eeb897ccd4a5a2dfe8f3