Update Readme.md

Readme.md

@@ -10,7 +10,7 @@ Create roles and assign roles to users. Sometimes it may even be useful to creat
 to get the finest granularity possible, while in other situations you will give the *asterisk* permission
 for admin kind of functionality.
 
-A Redis, MongoDB and In-Memory based backends are provided built-in in the module. There are other third party backends such as [*knex*](https://github.com/christophertrudel/node_acl_knex) based and [*firebase*](https://github.com/tonila/node_acl_firebase). There is also an alternative memory backend that supports [*regexps*](https://github.com/futurechan/node_acl-mem-regexp).
+A Redis, MongoDB and In-Memory based backends are provided built-in in the module. There are other third party backends such as [*knex*](https://github.com/christophertrudel/node_acl_knex) based, [*firebase*](https://github.com/tonila/node_acl_firebase) and [*elasticsearch*](https://github.com/adnanesaghir/acl-elasticsearch-backend). There is also an alternative memory backend that supports [*regexps*](https://github.com/futurechan/node_acl-mem-regexp).
 
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