docs(readme): Add reuse badge

Signed-off-by: Andy Scherzinger <info@andy-scherzinger.de>

Author: AndyScherzinger

README.md

@@ -5,5 +5,7 @@ SPDX-License-Identifier: CC0-1.0
 
 # OCS API Viewer
 
+[![REUSE status](https://api.reuse.software/badge/github.com/nextcloud/ocs_api_viewer)](https://api.reuse.software/info/github.com/nextcloud/ocs_api_viewer)
+
 This app can be used to view the OCS API specifications for any of the installed apps on your Nextcloud server.  
 Internally it relies on OpenAPI specifications that are distributed with the apps, so only apps that ship with an `openapi.json` file are supported.