Use backticks not vertical bars to denote variables in comments for /api

Bug: webrtc:12338
Change-Id: Ib97b2c3d64dbd895f261ffa76a2e885bd934a87f
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/226940
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Artem Titov <titovartem@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#34554}
diff --git a/api/rtc_error.h b/api/rtc_error.h
index 7cfd89a..8ca2249 100644
--- a/api/rtc_error.h
+++ b/api/rtc_error.h
@@ -176,7 +176,7 @@
 #endif  // WEBRTC_UNIT_TEST
 
 // Helper macro that can be used by implementations to create an error with a
-// message and log it. |message| should be a string literal or movable
+// message and log it. `message` should be a string literal or movable
 // std::string.
 #define LOG_AND_RETURN_ERROR_EX(type, message, severity)           \
   {                                                                \