[roll third_party/pigweed] pw_work_queue: Migrate API reference to Doxygen

Original-Bug: b/299147635
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/169830

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 17663e0b05afc4c..d17d40c437940d7
Roller-URL: https://ci.chromium.org/b/8770236537322037329
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I3b730c001035a4945fedf4d0948c63c09f9cc558
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/170039
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 17663e0..d17d40c 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 17663e0b05afc4c09b8208dab2c7403bce2c2ba8
+Subproject commit d17d40c437940d782b47eceb59574b0d7de9fb28