Ably MQTT adapter public beta

Ably has released the public beta of its MQTT adapter, allowing for greater interoperability and protocol agnosticism. The MQTT adaptor is now recommended for devices without a native Ably client library, such as Arduino platforms or C/C++ applications. It offers better performance with lower latency compared to using the Pubnub adapter, and connection state recovery not supported by Pusher. However, it does not support features like RETAIN messages or wildcard channel subscriptions that are not normally supported by Ably.