[third_party/pigweed] Roll 2 commits

afef6c3c7de6f5a pw_i2c: Revamp docs
6990ddbb08fdda2 docs: Update references to quickstart/bazel

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 7f4b2bf4dc94e42..afef6c3c7de6f5a
Roller-URL: https://ci.chromium.org/b/8752099822077513009
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I4164d06116ee10915240b9bd6ff0bf75f76ad5cf
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/200999
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 7f4b2bf..afef6c3 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 7f4b2bf4dc94e429bed96ff560e40dc80b221e62
+Subproject commit afef6c3c7de6f5a84465aad469a89556d0b34fbb