[roll] Roll fuchsia Revert "[docs] Use physzircon instead of zircon.elf"

This reverts commit d90bfe1ce266f46571efbd6b7390c152e518e062.

Reason for revert: broke check_markdown - b/416067778

Original change's description:
> [docs] Use physzircon instead of zircon.elf
>
> According to https://fuchsia.dev/fuchsia-src/development/kernel/kernel_debugging?hl=en#gathering_crash_information, we want `physzircon` not `zircon.elf`.
>
> Change-Id: Ib85b4df79ab62560b3f6ae863bd305e91a8d1962
> Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1269206
> Reviewed-by: Joshua Seaton <joshuaseaton@google.com>
> Commit-Queue: Carlos Pizano Uribe <cpu@google.com>

Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1270245
Original-Revision: 51b6cb1d8e1796a5d239480aaa25398bfcfdeb30
GitOrigin-RevId: 06169362d73427339b6f20786bbb7020f406ce94
Change-Id: I672586f64554dd4935bde2ec891b914dd812aec4
diff --git a/stem b/stem
index 56ebd5f..72bb7b0 100644
--- a/stem
+++ b/stem
@@ -8,7 +8,7 @@
              root=""
              remote="https://fuchsia.googlesource.com/fuchsia"
              gerrithost="https://fuchsia-review.googlesource.com"
-             revision="1bd2f09f8f7a83b7584d1375c2612abe935de070"
+             revision="51b6cb1d8e1796a5d239480aaa25398bfcfdeb30"
              />
   </imports>
   <projects>