Consider releases and/or version tags #875
Description
It seems like right now there are two meaningful branches in this repo: master (latest stable) and OpenAPI.next (under development). The versions directory holds old versions of the spec, but there's no long-term stable way to link to them -- if in the future, the versions directory is reorganized to, say, something like this --
versions
├── 1.x
│ └── 1.2.md
└── 2.x
├── 2.0.md
└── 2.1.md
then any links to versions/2.0.md would break. I do like the idea of including all old versions in the main repo, but it would be nice if master was tagged 2.0, so /blob/2.0/versions/2.0.md would work as a canonical link.