Versioning specs in the face of ambiguity

Versioning specs in the face of ambiguity

Tag the thread about how we intend to version the spec.  See
additional version discussion in [1,2,3,4,5].

[1]: Subject: Re: Initial Draft Release
     Date: Fri, 11 Sep 2015 13:58:08 -0700
     Message-ID: <20150911205808.GC5912@odin.tremily.us>
[2]: https://github.com/opencontainers/specs/issues/183
     New v0.1.1 tag doesn't match v0.1.0 in version.go
[3]: https://github.com/opencontainers/specs/pull/253
     Clarify backwards compatibility for major version 0
[4]: https://github.com/opencontainers/specs/pull/194
     Correct version from 0.1.0 to 0.1.1
[5]: https://github.com/opencontainers/specs/pull/278
     Project: document release process