This change was made so you don't have to export the API_DOCS environment variable  in order to have the meta yielded to the block, example:

```
    api_call(:get, v1_topic_path(topic.id), client_id: api_client_id ) do |doc|
      doc["description"] = 'Topic show'
      assert_response :success
      assert_v1_resource_response_body "topic", attrs_for_topic(topic)
    end
```
Before, if API_DOCS was not exported, because of this return https://github.com/satisfaction/api_docs/blob/699b0a3b5db727ffc6cdf63ed48a4d77a05e5178/lib/api_docs/test_helper.rb#L27, these lines were not executed:

```
      doc["description"] = 'Topic show'
      assert_response :success
      assert_v1_resource_response_body "topic", attrs_for_topic(topic)
```