[roll third_party/pigweed] pw_web: Add split/resize view guide in docs

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/211471
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https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: a90dc693295df7a..2ee9bbd280bae2f
Roller-URL: https://ci.chromium.org/b/8747102851796289681
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: Ieca47a543bebc219ef0638a4ea9c8e0f18b10149
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/211491
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
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diff --git a/third_party/pigweed b/third_party/pigweed
index a90dc69..2ee9bbd 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit a90dc693295df7a187fdbbfb0d73378baa0ee1c2
+Subproject commit 2ee9bbd280bae2f86054d3b0ca3b68c4eafda8ce