updated the readme

Author: alash3al

README.md

@@ -19,7 +19,7 @@ Features
 =========
 - Core data structure: `KV`, `List`, `Hashmap` with advanced implementations.
 - Advanced Publish/Subscribe using webhook and websocket!
-- Pluggable Storage Engine (`badger`, `bolt`)
+- Pluggable Storage Engine (`badger`, `bolt`, 'level')
 - Very compatible with any `redis client` including `redis-cli`
 - Standalone with no external dependencies
 - Helpers commands for `Time`, `Encode <hex|md5|sha1|sha256|sha512> <payload>`, `RANDINT`, `RANDSTR`