Make clear examples are just examples (#63)

reqwest-tracing/src/lib.rs

@@ -3,6 +3,8 @@
 //! Attach [`TracingMiddleware`] to your client to automatically trace HTTP requests.
 //!
 //! In this example we define a custom span builder to calculate the request time elapsed and we register the [`TracingMiddleware`].
+//!
+//! Note that Opentelemetry tracks start and stop already, there is no need to have a custom builder like this.
 //! ```rust
 //! use reqwest_middleware::Result;
 //! use task_local_extensions::Extensions;

reqwest-tracing/src/reqwest_otel_span_macro.rs

@@ -60,6 +60,7 @@
 /// # let request: &reqwest::Request = todo!();
 ///
 /// // Define a `time_elapsed` field as empty. It might be populated later.
+/// // (This example is just to show how to inject data - otel already tracks durations)
 /// reqwest_otel_span!(request, time_elapsed = tracing::field::Empty);
 ///
 /// // Define a `name` field with a known value, `AppName`.