update readme

Author: SethTisue

README.md

@@ -1,4 +1,4 @@
-# scala-async [![Build Status](https://travis-ci.org/scala/scala-async.svg?branch=master)](https://travis-ci.org/scala/scala-async) [<img src="https://img.shields.io/maven-central/v/org.scala-lang.modules/scala-async_2.12.svg?label=latest%20release%20for%202.12">](http://search.maven.org/#search%7Cga%7C1%7Cg%3Aorg.scala-lang.modules%20a%3Ascala-async_2.12) [<img src="https://img.shields.io/maven-central/v/org.scala-lang.modules/scala-async_2.13.0-RC1.svg?label=latest%20release%20for%202.13.0-RC1">](http://search.maven.org/#search%7Cga%7C1%7Cg%3Aorg.scala-lang.modules%20a%3Ascala-async_2.13.0-RC1)
+# scala-async [![Build Status](https://travis-ci.org/scala/scala-async.svg?branch=master)](https://travis-ci.org/scala/scala-async) [<img src="https://img.shields.io/maven-central/v/org.scala-lang.modules/scala-async_2.12.svg?label=latest%20release%20for%202.12">](http://search.maven.org/#search%7Cga%7C1%7Cg%3Aorg.scala-lang.modules%20a%3Ascala-async_2.12) [<img src="https://img.shields.io/maven-central/v/org.scala-lang.modules/scala-async_2.13.svg?label=latest%20release%20for%202.13">](http://search.maven.org/#search%7Cga%7C1%7Cg%3Aorg.scala-lang.modules%20a%3Ascala-async_2.13)
 
 ## Supported Scala versions
 
@@ -24,7 +24,7 @@ to match your project’s Scala binary version):
 </dependency>
 ```
 
-After adding a scala-async to your classpath, write your first `async` block:
+After adding scala-async to your classpath, write your first `async` block:
 
 ```scala
 import scala.concurrent.ExecutionContext.Implicits.global