Update reference.md

This is to pass check in CQ.

Change-Id: I6a360b0c68ca6b64e68a348f90f5826ed36f475a
Reviewed-on: https://gn-review.googlesource.com/c/gn/+/22420
Commit-Queue: Takuto Ikuta <tikuta@google.com>
Reviewed-by: Junji Watanabe <jwata@google.com>

docs/reference.md

diff --git a/docs/reference.md b/docs/reference.md
index 1ca0d1c..e05f015 100644
--- a/docs/reference.md
+++ b/docs/reference.md
@@ -8602,4 +8602,3 @@
     *   -v: Verbose logging.
     *   --version: Prints the GN version number and exits.
 ```
-