[roll third_party/pigweed] rust: Add rustdoc links for existing crates

Making these links consistent across modules will come with SEED-0102
implementation for these modules.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/159470

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 601f070ae1d8ba5..8451a05b3362a81
Roller-URL: https://ci.chromium.org/b/8774486547846249361
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: Ife66ce5a04df88ea72fb8f3f3a97fbd643e6f463
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/160070
Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index 601f070..8451a05 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 601f070ae1d8ba5458cdba00b518f141a8c930a1
+Subproject commit 8451a05b3362a814964fd925af85e6ffe6022eff