[roll third_party/pigweed] docs: Build style guide updates

- For the Bazel style guide, replace the Google-internal link with a
  link to the Bazel's public BUILD style guide.
- Update wording for the GN style section.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/77303

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: b0c5c998e1b3e18..26bc5a85a671265
Roller-URL: https://ci.chromium.org/b/8825671139447551521
Cq-Cl-Tag: roller-builder:pigweed-experimental-roller
Cq-Cl-Tag: roller-bid:8825671139447551521
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I55cc944f1877857c6bcd3402842d15289bb40a4a
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/77512
Bot-Commit: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>
Commit-Queue: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index b0c5c99..26bc5a8 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit b0c5c998e1b3e18898eeb5e1a54a56e8d8c2d714
+Subproject commit 26bc5a85a671265aaf87cb84f36948947c1b67a0