update README

README.md

@@ -10,7 +10,7 @@ SSDB is stable, production-ready and is widely used by many Internet companies i
 * Designed to store collection data
 * Persistent key-value, key-zset, key-map('hashmap') storage
 * Client API supports including [C++](http://www.ideawu.com/ssdb/docs/cpp/), [PHP](http://www.ideawu.com/ssdb/docs/php/), Python, Cpy, [Java](http://www.ideawu.com/ssdb/docs/java/), [nodejs](https://github.com/ideawu/ssdb/wiki/Documentation_nodejs_API), [Ruby](https://github.com/bsm/ssdb-rb), [Go](http://www.ideawu.com/ssdb/docs/go/)
-* Online backup, fast recover
+* Persistent queue service
 * **Replication(master-slave), load balance** [\[see wiki Replication\]](https://github.com/ideawu/ssdb/wiki/Replication)
 * <i>Future Features</i>
   * <i>Distributed</i>