Update mod.rs

Author: lalitb

opentelemetry/src/trace/mod.rs

@@ -191,7 +191,7 @@ use std::sync::PoisonError;
 
 // TODO - Move ExportError and TraceError to opentelemetry-sdk
 
-/// Marker trait for errors returned by exporters
+/// Trait for errors returned by exporters
 pub trait ExportError: std::error::Error + Send + Sync + 'static {
     /// The name of exporter that returned this error
     fn exporter_name(&self) -> &'static str;