Add nextcloud entry to README

README.md

@@ -22,6 +22,7 @@ Vouch Proxy supports many OAuth login providers and can enforce authentication t
 - [OAuth2 Server Library for PHP](https://github.com/vouch/vouch-proxy/issues/99)
 - [HomeAssistant](https://developers.home-assistant.io/docs/en/auth_api.html)
 - [OpenStax](https://github.com/vouch/vouch-proxy/pull/141)
+- [Nextcloud](https://docs.nextcloud.com/server/latest/admin_manual/configuration_server/oauth2.html)
 - most other OpenID Connect (OIDC) providers
 
 Please do let us know when you have deployed Vouch Proxy with your preffered IdP or library so we can update the list.