Update TODO example in the style guide.

This CL fixes the example in the WebRTC style guide and aligns it to
https://google.github.io/styleguide/cppguide.html#TODO_Comments.

Bug: None
Change-Id: Ic1d424b56f047d7d8266a76acb3fb881c8de4c50
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/328220
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#41206}
diff --git a/g3doc/style-guide.md b/g3doc/style-guide.md
index 8e6570a..57cb85c 100644
--- a/g3doc/style-guide.md
+++ b/g3doc/style-guide.md
@@ -65,7 +65,7 @@
 referencing a WebRTC bug, prefer using the URL form (excluding the scheme part):
 
 ```cpp
-// TODO(bugs.webrtc.org/12345): Delete the hack when blocking bugs are resolved.
+// TODO: bugs.webrtc.org/12345 - Delete the hack when blocking bugs are resolved.
 ```
 
 The short form used in commit messages, e.g. `webrtc:12345`, is discouraged.