update doucmentaiton comment

requests.go

@@ -14,6 +14,11 @@ func (c *Client) req(method, path string, body io.Reader, intercept func(*http.R
 	var retryBuf io.Reader
 
 	if body != nil {
+		// Because Request#Do closes closable streams, Seeker#Seek
+		// will fail on retry because stream is already  closed.
+		// This inhibits the closing of the passed stream on passing
+		// it to the RoundTripper and closes the stream after we
+		// are done with the body content.
 		if cl, ok := body.(io.Closer); ok {
 			body = closeInhibitor{body}
 			defer cl.Close()