document the callbacks

instrumentation/net/http/otelhttp/internal/request/body_wrapper.go

@@ -22,6 +22,9 @@ type BodyWrapper struct {
 }
 
 // NewBodyWrapper creates a new BodyWrapper.
+//
+// The onRead attribute is a callback that will be called every time the data
+// is read, with the number of bytes being read.
 func NewBodyWrapper(body io.ReadCloser, onRead func(int64)) *BodyWrapper {
 	return &BodyWrapper{
 		ReadCloser: body,

instrumentation/net/http/otelhttp/internal/request/resp_writer_wrapper.go

@@ -27,6 +27,9 @@ type RespWriterWrapper struct {
 }
 
 // NewRespWriterWrapper creates a new RespWriterWrapper.
+//
+// The onWrite attribute is a callback that will be called every time the data
+// is written, with the number of bytes that were written.
 func NewRespWriterWrapper(w http.ResponseWriter, onWrite func(int64)) *RespWriterWrapper {
 	return &RespWriterWrapper{
 		ResponseWriter: w,