[roll third_party/pigweed] docs: Remove file local TOCs

Furo theme has a right side table of contents and shows a warning if
'.. contents::' is used. This change removes those instances.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/57600

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 563946f9fa728da..ff4b74215a0a822
Roller-URL: https://ci.chromium.org/b/8838518607219761408
Cq-Cl-Tag: roller-builder:pigweed-experimental-roller
Cq-Cl-Tag: roller-bid:8838518607219761408
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I0c4ca74ed6566034fa799fd091ce050976b433e6
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/57602
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 563946f..ff4b742 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 563946f9fa728da641a406dfdc7fa724abb770d2
+Subproject commit ff4b74215a0a8223f2c3ccca0e5340decd010f5e