[DOCS] should use setPostFilter instead of setFilter

docs/java-api/search.asciidoc

@@ -23,7 +23,7 @@ SearchResponse response = client.prepareSearch("index1", "index2")
         .setTypes("type1", "type2")
         .setSearchType(SearchType.DFS_QUERY_THEN_FETCH)
         .setQuery(QueryBuilders.termQuery("multi", "test"))             // Query
-        .setFilter(FilterBuilders.rangeFilter("age").from(12).to(18))   // Filter
+        .setPostFilter(FilterBuilders.rangeFilter("age").from(12).to(18))   // Filter
         .setFrom(0).setSize(60).setExplain(true)
         .execute()
         .actionGet();