docs(readme): update link

Author: Red-Asuka

README.md

@@ -143,7 +143,7 @@ Please make sure to read the [Contributing Guide](https://github.com/emqx/MQTTX/
 
 ## Resources
 
-- [MQTT client programming](https://www.emqx.com/en/blog/tag/mqtt-client-programming)
+- [MQTT Programming](https://www.emqx.com/en/blog/category/mqtt-programming)
 
   A series of blogs to help developers get started quickly with MQTT in PHP, Node.js, Python, Golang, and other programming languages.