Adopt development conventions

README.md

@@ -6,3 +6,11 @@ To report issues, questions, or feature requests, please either:
 * File a Github issue, seeing first if it is already filed, [here](https://github.com/dfxml-working-group/dfxml_schema).
 * Email the dfxml@nist.gov mailing list.  If you wish to join the mailing list, send an email to [dfxml-subscribe@nist.gov](mailto:dfxml-subsribe@nist.gov) (no subject or message body is necessary), and a moderator will grant access.
 
+
+## Development conventions
+
+Following version 1.2.0, this project adopted the following development conventions:
+
+* [Semantic Versioning 2.0.0](https://semver.org/).
+* A branching model as described [here](https://nvie.com/posts/a-successful-git-branching-model/), with the additional convention that a "release" branch will initially present `-beta.n` releases for a period of at least two weeks for comment.
+  - When a feature branch is merged into `develop`, any associated Github Issues may be considered resolved.