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