[roll] Roll fuchsia [bt] Adding more description to comment

I learned about this usage during a meeting and I think
it should be documented so the knowledge will not be lost.

Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/683626
Original-Revision: cc84f50c811f67accca4fc38501651bc07f6698a
GitOrigin-RevId: 2e51e0807dcf1158be2e451aa330096286e4f312
Change-Id: I4180160204fef943b669ce367549d6102cc71373
diff --git a/stem b/stem
index c11ec8b..cf53445 100644
--- a/stem
+++ b/stem
@@ -10,7 +10,7 @@
              githooks=""
              remote="https://fuchsia.googlesource.com/fuchsia"
              gerrithost="https://fuchsia-review.googlesource.com"
-             revision="eff5d76d4018dc0e3f63d2e86cdaa1901e8a6787"/>
+             revision="cc84f50c811f67accca4fc38501651bc07f6698a"/>
   </projects>
   <hooks>
     <hook name="install-environment"