Update docs

Author: fredsted

docs/api/users.md

@@ -5,6 +5,8 @@
 * Requires [authentication](/api/about.html#api-key)
 * Requires Administrator user type
 
+If part of a SSO-enabled Webhook.site Team, the user is sent a login URL where they can log in immediately. Otherwise, they are sent a link to a page where they can set up their profile and password.
+
 #### Request
 
 **POST** `https://webhook.site/users/invite`