Add DragonflyDB info to Redis README and remove DragonflyDB file

- Added DragonflyDB usage details to Redis README
- Removed the DragonflyDB file
- No extra tests were added for DragonflyDB; existing Redis tests work for it

redis/config.go

@@ -6,6 +6,8 @@ import (
 )
 
 // Config defines the config for storage.
+//
+// Dragonfly and Redis share the same config
 type Config struct {
 	// Host name where the DB is hosted
 	//