Add ids query doc.

docs/Query/Ids.md

+# Ids Query
+
+> More info about ids query is in the [official elasticsearch docs][1]
+
+Filters documents that only have the provided ids.
+
+## Simple example
+
+```JSON
+{
+    "ids" : {
+        "type" : "my_type",
+        "values" : ["1", "4", "100"]
+    }
+}
+```
+
+In DSL:
+
+```php
+$idsQuery = new IdsQuery(['1', '4', '100'], ['type' => 'my_type']);
+
+$search = new Search();
+$search->addQuery($idsQuery);
+
+$queryArray = $search->toArray();
+```
+
+[1]: https://www.elastic.co/guide/en/elasticsearch/reference/current/query-dsl-ids-query.html