[enh] add suggestions to brave engine

Suggestions should be added too.

    suggestion_xpath: //div[@class="text-gray h6"]/a

You can try it with:

    !brave recurzuoin

Suggested-by: @allendema in https://github.com/searx/searx/issues/2857#issuecomment-904837023
Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

searx/settings.yml

@@ -1585,6 +1585,7 @@ engines:
     url_xpath: //div[@class="snippet fdb"]/a/@href
     title_xpath: //span[@class="snippet-title"]
     content_xpath: //p[1][@class="snippet-description"]
+    suggestion_xpath: //div[@class="text-gray h6"]/a
     categories: general
     about:
       website: https://brave.com/search/