Allow some solr query options in the config file

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

@@ -109,8 +109,13 @@ docspell.server {
       commit-within = 1000
       # If true, logs request and response bodies
       log-verbose = false
+      # The defType parameter to lucene that defines the parser to
+      # use. You might want to try "edismax" or look here:
+      # https://lucene.apache.org/solr/guide/8_4/query-syntax-and-parsing.html#query-syntax-and-parsing
+      def-type = "lucene"
+      # The default combiner for tokens. One of {AND, OR}.
+      q-op = "OR"
     }
-
   }
 
   # Configuration for the backend.