fix(service/minitrace): update doc (#2621)

core/src/layers/minitrace.rs

@@ -64,32 +64,29 @@ use crate::*;
 /// fn main() -> Result<(), Box<dyn Error + Send + Sync + 'static>> {
 /// let collector = {
 /// let (span, collector) = minitrace::Span::root("op");
-/// let _g = span.set_local_parent();
 /// let runtime = tokio::runtime::Runtime::new()?;
-///
-/// runtime.block_on(async {
-/// let _ = dotenvy::dotenv();
-/// let op = Operator::from_env::<services::Memory>()
-/// .expect("init operator must succeed")
-/// .layer(MinitraceLayer)
-/// .finish();
-///
-/// op.write("test", "0".repeat(16 * 1024 * 1024).into_bytes())
-/// .await
-/// .expect("must succeed");
-/// op.stat("test").await.expect("must succeed");
-/// op.read("test").await.expect("must succeed");
-/// });
+/// runtime.block_on(
+/// async {
+/// let _ = dotenvy::dotenv();
+/// let op = Operator::from_env::<services::Memory>()
+/// .expect("init operator must succeed")
+/// .layer(MinitraceLayer)
+/// .finish();
+/// op.write("test", "0".repeat(16 * 1024 * 1024).into_bytes())
+/// .await
+/// .expect("must succeed");
+/// op.stat("test").await.expect("must succeed");
+/// op.read("test").await.expect("must succeed");
+/// }
+/// .in_span(Span::enter_with_parent("test", &span)),
+/// );
 /// collector
 /// };
-///
 /// let spans = block_on(collector.collect());
-///
 /// let bytes =
 /// minitrace_jaeger::encode("opendal".to_owned(), rand::random(), 0, 0, &spans).unwrap();
 /// minitrace_jaeger::report_blocking("127.0.0.1:6831".parse().unwrap(), &bytes)
 /// .expect("report error");
-///
 /// Ok(())
 /// }
 /// ```