Add maps and saml plugins and add some hints to the readme

README.md

+# Setup SAML with Keycloak
+
+Follow [this guide](https://rmm.li/wiki/doku.php?id=linux_server_manuals:nextcloud_saml_authentication_against_keycloak) and pay attention to these:
+
+- To map existing users, make sure that the username in Keycloak and Nextcloud is the same
+- In Nextcloud disable the option that the NameID response needs to be encrypted

defaults/main.yml

@@ -30,6 +30,7 @@ nextcloud_plugins:
   - groupfolders
   - group_everyone
   - impersonate
+  - maps
   - metadata
   - news
   - notes
@@ -49,6 +50,7 @@ nextcloud_plugins:
   - text
   - theming
   - twofactor_totp
+  - user_saml
 nextcloud_pinned_plugin_versions: []
 coturn:
   - secret: somerandomstring