[DOC]auth_oidc: more options for token maps

auth_oidc/readme/CONFIGURE.md

@@ -57,7 +57,8 @@ In Odoo, create a new Oauth Provider with the following parameters:
 - Provider name: Keycloak (or any name you like that identify your
   keycloak provider)
 - Auth Flow: OpenID Connect (authorization code flow)
-- Token Map : `preferred_username:user_id`
+- Token Map : many options are possible like `preferred_username:user_id` or
+  `email:user_id` . This can be combined
 - Client ID: the same Client ID you entered when configuring the client
   in Keycloak
 - Client Secret: found in keycloak on the client Credentials tab