Update README.md

README.md

@@ -3,5 +3,17 @@ This is a Webex Teams console chat client. It uses Cisco's undocumented WebSocke
 
 This client currently only support chats.
 
+## Authentication
+For now you have to provide to webinc a valid `authorization` token. To obtain one, you can go to https://developer.webex.com/login, Documentation, Api Reference, choose any API endpoint and you will be able to copy the `Authorization` token on the right.
+
+Then, create a `webinc.conf` file next to webinc and add the authorization token. This file is in [YAML format](https://fr.wikipedia.org/wiki/YAML).
+
+Example:
+```
+$ cat webinc.conf
+- key: auth-token
+  value: NDRlOTZhOGQtMWY0ZS00MjMyLWIzNzItMjVlOGU5NjBmZGNkMWMwY2JmMzItMDVl_PF84_consumer
+```
+
 ## License
 GNU GPLv3