Fix broken link (#89)

README.md

@@ -123,7 +123,7 @@ locations below:
 |                                                                Location                                                                 |
 | :-------------------------------------------------------------------------------------------------------------------------------------: |
 |          [AWS IoT Device SDK for Embedded C](https://github.com/aws/aws-iot-device-sdk-embedded-C#releases-and-documentation)           |
-| [FreeRTOS.org](https://freertos.org/Documentation/api-ref/device-defender-for-aws-iot-embedded-sdk/docs/doxygen/output/html/index.html) |
+| [GitHub.io](https://aws.github.io/Device-Defender-for-AWS-IoT-embedded-sdk/v1.3.0/) |
 
 Note that the latest included version of the AWS IoT Device Defender library may
 differ across repositories.