Merge pull request #2857 from L-607/L-main

fix wrong sql

Author: Meggielqk

en_US/data-integration/assets/kafka_dynamic_topic_sql.png

@@ -196,7 +196,7 @@ To prevent leakage of other system environment variables, the names of environme
 
    ```sql
    SELECT
-     getenv(`KAFKA_TOPIC`) as kafka_topic,
+     getenv('KAFKA_TOPIC') as kafka_topic,
      payload
    FROM
      "t/#"

en_US/data-integration/data-bridge-kafka.md

@@ -194,7 +194,7 @@ EMQX v5.7.2 引入了一项新功能，可以在 SQL 处理阶段将从设置的
 
    ```sql
    SELECT
-     getenv(`KAFKA_TOPIC`) as kafka_topic,
+     getenv('KAFKA_TOPIC') as kafka_topic,
      payload
    FROM
      "t/#"