[roll] Roll fuchsia [gndoc] Update GN build arguments documentation

Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/396047
Original-Revision: 120887f30595b45b3557b6a8fd6a2933675b8712
GitOrigin-RevId: cced58b0c7f7c4d6c5b4abb3bdb43a7d43afb207
Change-Id: Ia1d44a0ec754a1afe12cf54e8f56ffa67b81a965
diff --git a/stem b/stem
index e4f58a8..cb04b83 100644
--- a/stem
+++ b/stem
@@ -10,7 +10,7 @@
              githooks=""
              remote="https://fuchsia.googlesource.com/fuchsia"
              gerrithost="https://fuchsia-review.googlesource.com"
-             revision="200b6eecddc440ab3e8fea3742a18b2e03c8e06e"/>
+             revision="120887f30595b45b3557b6a8fd6a2933675b8712"/>
   </projects>
   <hooks>
     <hook name="install-fx"