doc: Add change history for 0.6.0-beta4 (#311)

Adds history of change for 0.6.0-beta4, related to supporting rendering
property.

Author: absoludity

docs/untp-data-model/changes-v0.6.0-beta4.md

@@ -0,0 +1,27 @@
+These changes are the changes from v0.6.0-beta1 to v0.6.0-beta4.
+
+The only change is the addition of the `RenderTemplate2024` and
+`WebRenderingTemplate2022` types and their inclusion in each of the VCs.
+
+This is so that DPPs or other VCs which include a `renderMethod` property
+containing an object with a `template` or `url` etc., won't be rejected as
+invalid jsonld (due to the terms not being defined in the context).
+
+Both the types have the `name` property set as an ID so that they will be blue classes and [included in the context](https://github.com/jargon-sh/issues/issues/30).
+
+See https://github.com/uncefact/spec-untp/issues/309 for the issue details.
+
+Each VC model had the following change:
+- Update the import to core 0.6.0-beta4
+- Added the following to the definition of the model so that the type is included in the model's context:
+```
+// The following two entities ensure that render templates
+// won't leave the credential as invalid jsonld
+RenderTemplate2024:untp.RenderTemplate2024
+  #hideClass
+
+WebRenderingTemplate2022:untp.WebRenderingTemplate2022
+  #hideClass
+```
+- Saved the model
+- Released 0.6.0-beta4 for the model