Add note to Mosquitto Docker instructions (#1295)
Add note to Mosquitto Docker instructions (#1295)

* Add note to Docker instructions in README

* Address comment

* Fix comment

Co-authored-by: SarenaAWS <93d3d3d909f752df01ee3ccf256948db4022e71f@users.noreply.github.com>

Co-authored-by: SarenaAWS <93d3d3d909f752df01ee3ccf256948db4022e71f@users.noreply.github.com>
aws/aws-iot-device-sdk-embedded-C,aws/aws-iot-device-sdk-embedded-C,aws/aws-iot-device-sdk-embedded-C