Update default async behavior to True

Read async behavior from envvar `MQ_ASYNC_CONSUMERS`
Update documentation to reflect changes in default and configuration

README.md

@@ -67,17 +67,26 @@ A response may be sent via:
 ```
 Where `<queue>` is the queue to which the response will be published, and `data` is a `bytes` response (generally a `base64`-encoded `dict`).
 
-### [BETA] Asynchronous Consumers
+### Asynchronous Consumers
+By default, async-based consumers handling based on `pika.SelectConnection` will
+be used
 
-Now there is a support for async-based consumers handling based on `pika.SelectConnection`
+#### Override use of async consumers
 
-#### Enabling in a code
+There are a few methods to disable use of async consumers/subscribers.
 
-To enable creation of async consumers/subscribers, set the class-attribute `async_consumers_enabled` to True:
+1. To disable async consumers for a particular class/object, 
+set the class-attribute `async_consumers_enabled` to `False`:
 
-```python
-from neon_mq_connector import MQConnector
+   ```python
+   from neon_mq_connector import MQConnector
+
+   class MQConnectorChild(MQConnector):
+      async_consumers_enabled  = True
+   ```
+2. To disable the use of async consumers at runtime, set the `MQ_ASYNC_CONSUMERS`
+envvar to `False`
 
-class MQConnectorChild(MQConnector):
-   async_consumers_enabled  = True
-```
+   ```shell
+   export MQ_ASYNC_CONSUMERS=false
+   ```

neon_mq_connector/connector.py

@@ -65,7 +65,7 @@ class MQConnector(ABC):
     __max_consumer_restarts__ = -1
     __consumer_join_timeout__ = 3
 
-    async_consumers_enabled = False
+    async_consumers_enabled = os.environ.get("MQ_ASYNC_CONSUMERS", True)
 
     @staticmethod
     def init_config(config: Optional[dict] = None) -> dict: