Fix issues with doc tests in kafka
@@ -221,7 +221,7 @@ pub(crate) struct Config {
///
/// Example:
///
- /// ```
+ /// ```json
/// "transactional": {
/// "commit_interval": nanos::from_seconds(5)
/// }
@@ -229,7 +229,7 @@ pub(crate) struct Config {
///
/// - `custom`: Configure the connector yourself as you like, by providing your own set of `rdkafka_options`. You should know what you are doing when using this.
///
- /// Example: ```
+ /// Example: ```json
/// "custom": {
/// "rdkafka_options": {
/// "enable.auto.commit": false
