Merge pull request #12 from bbc/philipn-versioning-approach

Add API Versioning section to README

README.md

@@ -65,5 +65,8 @@ Flows in the store are assumed to be immutable: once a grain has been written to
 
 When it becomes necessary to mutate content, for example reversioning content or performing production operations, the Flow ID (and potentially Source ID) will change. Various scenarios are explored in the [Practical Guidance for Media](https://specs.amwa.tv/ms-04/releases/v1.0.0/docs/3.0._Practical_Guidance_for_Media.html) section of AMWA MS-04.
 
+### API Versioning
+The API is versioned using a major and minor version number. A breaking change results in a major version increment and the minor version is reset to 0. Features such new endpoints or new (optional) data properties result in a minor version increment. Other changes such as bug fixes and documentation changes do not result in version updates. Note that the version may change frequently whilst the API is still under development!
+
 ## Get in touch
 If you'd like to know more about our work on TAMS, talk about our implementations or start a collaboration, contact us on <[email protected]>.