Added docs for AsyncAws

Author: Nyholm

README.md

@@ -96,6 +96,7 @@ to interact with your storage.
 1. [Getting started](https://github.com/thephpleague/flysystem-bundle/blob/master/docs/1-getting-started.md)
 2. Cloud storage providers:
    [Azure](https://github.com/thephpleague/flysystem-bundle/blob/master/docs/2-cloud-storage-providers.md#azure),
+   [AsyncAws S3](https://github.com/thephpleague/flysystem-bundle/blob/master/docs/2-cloud-storage-providers.md#asyncaws-s3),
    [AWS S3](https://github.com/thephpleague/flysystem-bundle/blob/master/docs/2-cloud-storage-providers.md#aws-s3),
    [DigitalOcean Spaces](https://github.com/thephpleague/flysystem-bundle/blob/master/docs/2-cloud-storage-providers.md#digitalocean-spaces),
    [Scaleway Object Storage](https://github.com/thephpleague/flysystem-bundle/blob/master/docs/2-cloud-storage-providers.md#scaleway-object-storage),

docs/2-cloud-storage-providers.md

@@ -5,6 +5,7 @@ including many cloud storage providers. This bundle provides the same level of s
 cloud providers by providing corresponding adapters in the configuration.
 
 * [Azure](#azure)
+* [AsyncAws S3](#asyncaws-s3)
 * [AWS S3](#aws-s3)
 * [DigitalOcean Spaces](#digitalocean-spaces)
 * [Scaleway Object Storage](#scaleway-object-storage)
@@ -35,6 +36,29 @@ flysystem:
                 prefix: 'optional/path/prefix'
 ```
 
+## AsyncAws S3
+
+### Installation
+
+```
+composer require async-aws/flysystem-s3
+```
+
+### Usage
+
+```yaml
+# config/packages/flysystem.yaml
+
+flysystem:
+    storages:
+        users.storage:
+            adapter: 'asyncaws'
+            options:
+                client: 'aws_client_service' # The service ID of the AsyncAws\S3\S3Client instance
+                bucket: 'bucket_name'
+                prefix: 'optional/path/prefix'
+```
+
 ## AWS S3
 
 ### Installation