Add installation instructions

Author: 36864

README.md

@@ -1,6 +1,8 @@
 # flysystem-msgraph
 A flysystem 3.0 adapter for Sharepoint 365 / OneDrive using Microsoft Graph API with support for uploading large files
 
+# Installation
+```composer require shitwareltd/flysystem-msgraph```
 
 # Usage
 Instantiate the adapter by passing in an instance of `\Microsoft\Graph\Graph` and the DriveId of the drive you want to use.