Update CHANGELOG.md for the resumable file upload API

CHANGELOG.md

@@ -9,8 +9,16 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- The file transmission API was extended to support resumable file uploads via an LinkAhead
+  Upload Protocol. The currently planned protocol is the TUS protocol. The resumable upload
+  API is still in alpha status.
+
 ### Changed
 
+- The file transmission API was split from the entity API into its own proto file (v1alpha).
+  The entity API version is incremented to v2alpha1. is currently identical to v1 but
+  lacking the file transmission API). 
+
 ### Deprecated
 
 ### Removed