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

Bug: webrtc:12338
Change-Id: I02613d9fca45d00e2477f334b7a0416e7912e26b
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/227037
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Artem Titov <titovartem@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#34621}
diff --git a/modules/audio_coding/neteq/packet.h b/modules/audio_coding/neteq/packet.h
index 4455494..0c6f204 100644
--- a/modules/audio_coding/neteq/packet.h
+++ b/modules/audio_coding/neteq/packet.h
@@ -84,8 +84,8 @@
 
   // Packets should generally be moved around but sometimes it's useful to make
   // a copy, for example for testing purposes. NOTE: Will only work for
-  // un-parsed packets, i.e. |frame| must be unset. The payload will, however,
-  // be copied. |waiting_time| will also not be copied.
+  // un-parsed packets, i.e. `frame` must be unset. The payload will, however,
+  // be copied. `waiting_time` will also not be copied.
   Packet Clone() const;
 
   Packet& operator=(Packet&& b);