Reorganize docs about configuration

website/site/content/docs/configure/registration.md

@@ -0,0 +1,44 @@
++++
+title = "Registration"
+insert_anchor_links = "right"
+description = "Describes the configuration file and shows all default settings."
+weight = 80
+template = "docs.html"
++++
+
+# Registration Options
+
+This defines if and how new users can create accounts. There are 3
+options:
+
+- *closed* no new user can sign up
+- *open* new users can sign up
+- *invite* new users can sign up but require an invitation key
+
+This applies only to the REST sevrer component.
+
+``` bash
+docspell.server.backend.signup {
+  mode = "open"
+
+  # If mode == 'invite', a password must be provided to generate
+  # invitation keys. It must not be empty.
+  new-invite-password = ""
+
+  # If mode == 'invite', this is the period an invitation token is
+  # considered valid.
+  invite-time = "3 days"
+}
+```
+
+The mode `invite` is intended to open the application only to some
+users. The admin can create these invitation keys and distribute them
+to the desired people. For this, the `new-invite-password` must be
+given. The idea is that only the person who installs docspell knows
+this. If it is not set, then invitation won't work. New invitation
+keys can be generated from within the web application or via REST
+calls (using `curl`, for example).
+
+``` bash
+curl -X POST -d '{"password":"blabla"}' "http://localhost:7880/api/v1/open/signup/newinvite"
+```