[roll third_party/pigweed] pw_web: Add docs section for log viewer component

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/155050

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 9deeaa745e2ff42..29a2140fcebf8b0
Roller-URL: https://ci.chromium.org/b/8775286175028473745
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I7138820b956cb4e6f8c785f8e7f46e5ef99cdf8a
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/156353
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 9deeaa7..29a2140 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 9deeaa745e2ff42a65024cac2dc4f172c8f647ce
+Subproject commit 29a2140fcebf8b0e118aae3541a83e63f91d0560