[roll third_party/pigweed] docs: Revamp Doxygen style guide

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/202590

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 19d58a7afb51ced..3fbcf41574028ef
Roller-URL: https://ci.chromium.org/b/8750808098512017425
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: Id8cd028562a16019d2cf3de33a6ac7d25f8f0bc4
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/203410
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 19d58a7..3fbcf41 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 19d58a7afb51cedb9523e056ade5c8d6736713a7
+Subproject commit 3fbcf41574028ef01717ba5c35ee86c587182f4e