added akka-http on readme

Author: tsuyoshizawa

README.md

@@ -2,7 +2,7 @@
 
 [The OAuth 2.0](http://tools.ietf.org/html/rfc6749) server-side implementation written in Scala.
 
-This provides OAuth 2.0 server-side functionality and supporting function for [Play Framework](http://www.playframework.com/). Play Framework 2.2, 2.3, 2.4 and 2.5 are now supported.
+This provides OAuth 2.0 server-side functionality and supporting function for [Play Framework](http://www.playframework.com/) and [Akka HTTP](http://akka.io/).
 
 The idea of this library originally comes from [oauth2-server](https://github.com/yoichiro/oauth2-server) which is Java implementation of OAuth 2.0.
 
@@ -21,38 +21,48 @@ and an access token type called [Bearer](http://tools.ietf.org/html/rfc6750).
 
 If you'd like to use this with Play Framework, add "play2-oauth2-provider" to library dependencies of your project.
 
-### For Play Framework 2.5
+### Play Framework
+#### 2.5
 
 ```scala
 libraryDependencies ++= Seq(
   "com.nulab-inc" %% "play2-oauth2-provider" % "0.18.0"
 )
 ```
 
-### For Play Framework 2.4
+#### 2.4
 
 ```scala
 libraryDependencies ++= Seq(
   "com.nulab-inc" %% "play2-oauth2-provider" % "0.16.1"
 )
 ```
 
-### For Play Framework 2.3
+#### 2.3
 
 ```scala
 libraryDependencies ++= Seq(
   "com.nulab-inc" %% "play2-oauth2-provider" % "0.14.0"
 )
 ```
 
-### For Play Framework 2.2
+#### 2.2
 
 ```scala
 libraryDependencies ++= Seq(
   "com.nulab-inc" %% "play2-oauth2-provider" % "0.7.4"
 )
 ```
 
+### Akka HTTP
+#### 2.4
+
+```scala
+libraryDependencies ++= Seq(
+  "com.nulab-inc" %% "akka-http-oauth2-provider" % "0.18.0"
+)
+```
+
 ### Other frameworks
 
 Add "scala-oauth2-core" instead. In this case, you need to implement your own OAuth provider working with web framework you use.