[fix] remove btdigg - see https://torrentfreak.com/btdigg-shut-down-due-to-torrent-spam-for-now-160711/

searx/settings.yml

     disabled : True
     shortcut : bb
 
-  - name : btdigg
-    engine : btdigg
-    shortcut : bt
-
   - name : crossref
     engine : json_engine
     paging : True