README.md in oauth2_api_client-2.0.0 vs README.md in oauth2_api_client-2.1.0

- old
+ new

@@ -1,11 +1,11 @@
 # oauth2_api_client
 
 [![Build Status](https://secure.travis-ci.org/mrkamel/oauth2_api_client.svg?branch=master)](http://travis-ci.org/mrkamel/oauth2_api_client)
 [![Gem Version](https://badge.fury.io/rb/oauth2_api_client.svg)](http://badge.fury.io/rb/oauth2_api_client)
 
-Oauth2ApiClient is small, but powerful client around
+Oauth2ApiClient is a small, but powerful client around
 [oauth2](https://github.com/oauth-xx/oauth2) and
 [http-rb](https://github.com/httprb/http) to interact with APIs which use
 oauth2 for authentication.
 
 ```ruby
@@ -30,9 +30,12 @@
     cache: Rails.cache, # optional,
     max_token_ttl: 1800 # optional
   )
 )
 ```
+
+Please note, `get`, `post`, `put`, etc. will raise `Oauth2ApiClient::HttpError`
+unless the response code is 2xx.
 
 ## Install
 
 Add this line to your application's Gemfile:
 