[roll third_party/pigweed] pw_toolchain: Small docs update

Provide some guidance on how to depend on arm_none_eabi_gcc_support when
building with Bazel.

Original-Fixed: b/300471936
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/189278

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 4207f9a237cf92e..0316a4d4ae164d4
Roller-URL: https://ci.chromium.org/b/8757518381653479329
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I81541be2af6fd66dedbb8a92f1acf3ce6d0d3e43
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/189671
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index 4207f9a..0316a4d 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 4207f9a237cf92e3b73dc9dbbe252f4aa6e6f8bc
+Subproject commit 0316a4d4ae164d4aadc9c43533a9ba484abfad2c