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/candidate.cc b/api/candidate.cc
index d5fe3a0..ad65121 100644
--- a/api/candidate.cc
+++ b/api/candidate.cc
@@ -92,7 +92,7 @@
   //            (2^8)*(local preference) +
   //            (2^0)*(256 - component ID)
 
-  // |local_preference| length is 2 bytes, 0-65535 inclusive.
+  // `local_preference` length is 2 bytes, 0-65535 inclusive.
   // In our implemenation we will partion local_preference into
   //              0                 1
   //       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5