[feat] mediathekviewweb: add description to queried fields (#6717)

Queries like `!mvw hercule poirot` usually yield no results if the `description`
is not also included in the search.

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

searx/engines/mediathekviewweb.py

@@ -37,6 +37,7 @@ def request(query: str, params: "OnlineParams"):
                 "fields": [
                     "title",
                     "topic",
+                    "description",
                 ],
                 "query": query,
             },