Merge pull request #103 from dart-lang/mit-mit-patch-1

Clarify proto3

README.md

@@ -5,14 +5,16 @@
 
 This repository provides a plugin for the [protoc
 compiler](https://developers.google.com/protocol-buffers/docs/cpptutorial#compiling-your-protocol-buffers).
-It generates Dart files for working with data in protocol buffers format. At
-this time we only support
-[proto2](https://developers.google.com/protocol-buffers/docs/proto), but proto3
-may work in simple cases due to backwards compatibility.
+It generates Dart files for working with data in protocol buffers format.
 
 Requirements
 ------------
 
+We only support the full [proto2](https://developers.google.com/protocol-buffers/docs/proto)
+schema. Proto3 should work due to backwards compatibility. See
+[this issue list](https://github.com/dart-lang/protobuf/issues?q=is%3Aissue+is%3Aopen+label%3Aproto3)
+for proto3 schema features which are currently missing.
+
 To compile a .proto file, you must use the 'protoc' command which is [installed
 separately](https://developers.google.com/protocol-buffers/docs/downloads).
 Protobuf 3.0.0 or above is required.