Create a place for admin routes

And move re-creation of fulltext index in this place.

modules/restserver/src/main/resources/reference.conf

@@ -111,6 +111,18 @@ docspell.server {
     }
   }
 
+  # This is a special endpoint that allows some basic administration.
+  #
+  # It is intended to be used by admins only, that is users who
+  # installed the app and have access to the system. Normal users
+  # should not have access and therefore a secret must be provided in
+  # order to access it.
+  admin-endpoint {
+    # The secret. If empty, the endpoint is disabled.
+    secret = ""
+
+  }
+
   # Configuration of the full-text search engine.
   full-text-search {
     # The full-text search feature can be disabled. It requires an