[MODEL] Added information about elasticsearch-dsl to the README

Closes elastic#574

[ci skip]

Author: bogdanvlviv

elasticsearch-model/README.md

@@ -320,8 +320,8 @@ response.results.first.highlight.title
 # ["Quick brown <em>fox</em>"]
 ```
 
-You can pass any object which implements a `to_hash` method, or you can use your favourite JSON builder
-to build the search definition as a JSON string:
+You can pass any object which implements a `to_hash` method, which is called automatically,
+so you can use a custom class or your favourite JSON builder to build the search definition:
 
 ```ruby
 require 'jbuilder'
@@ -341,6 +341,25 @@ response.results.first.title
 # => "Quick brown fox"
 ```
 
+Also, you can use the [**`elasticsearch-dsl`**](https://github.com/elastic/elasticsearch-ruby/tree/master/elasticsearch-dsl) library, which provides a specialized Ruby API for
+the Elasticsearch Query DSL:
+
+```ruby
+require 'elasticsearch/dsl'
+
+query = Elasticsearch::DSL::Search.search do
+  query do
+    match :title do
+      query 'fox dogs'
+    end
+  end
+end
+
+response = Article.search query
+response.results.first.title
+# => "Quick brown fox"
+```
+
 ### Index Configuration
 
 For proper search engine function, it's often necessary to configure the index properly.