Update span.rs

Co-authored-by: Zhongyang Wu <zhongyang.wu@outlook.com>

Author: hdost

opentelemetry/src/trace/span.rs

@@ -154,7 +154,7 @@ pub trait Span {
     where
         T: Into<Cow<'static, str>>;
 
-    /// Adds a link to another `SpanContext`.
+    /// Adds [`Link`] to another [`SpanContext`].
     ///
     /// This method allows linking the current span to another span, identified by its `SpanContext`. Links can be used
     /// to connect spans from different traces or within the same trace. Attributes can be attached to the link to
@@ -167,6 +167,7 @@ pub trait Span {
     /// * `attributes` - A vector of `KeyValue` pairs that describe additional attributes of the link. These attributes
     ///   can include any contextual information relevant to the link between the spans.
     ///
+    /// [`Link`]: crate::trace::Link
     fn add_link(&mut self, span_context: SpanContext, attributes: Vec<KeyValue>);
 
     /// Signals that the operation described by this span has now ended.