Mention that OAuth2 currently only works with dart:io.

R=rnystrom@google.com
BUG=7445

Review URL: https://codereview.chromium.org//61393004

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@30296 260f80e4-7a28-3924-810f-c04153c831b5
diff --git a/pubspec.yaml b/pubspec.yaml
index 4d6fda6..b0d701d 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -5,7 +5,7 @@
 description: >
   A client library for authenticating with a remote service via OAuth2 on
   behalf of a user, and making authorized HTTP requests with the user's
-  OAuth2 credentials.
+  OAuth2 credentials. Currently only works with dart:io.
 dependencies:
   http: ">=0.9.0 <0.10.0"
 dev_dependencies: