Improve version info shown in the doc of SQL Gateway

In the sql gateway doc, In the part of https://nightlies.apache.org/flink/flink-docs-master/zh/docs/dev/table/sql-gateway/overview/#starting-the-sql-gateway,

$ curl http://localhost:8083/v1/info
{"productName":"Apache Flink","version":"1.16-SNAPSHOT"} 

the version will be always 1.16-SNAPSHOT whatever the Flink version is . It may cause use feel confused. 

For user, when it's for flink 1.17 doc, it should show "version":"1.17"