[roll third_party/pigweed] pw_bluetooth_sapphire: Add sales pitch & roadmap docs

Original-Bug: 312287470
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/181834

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 583b47ec7ced635..c6a478ddc4d8374
Roller-URL: https://ci.chromium.org/b/8762977643796096689
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: Iedf55a37c4a4bed4fa1f25bda368e1413e194c15
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/183174
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 583b47e..c6a478d 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 583b47ec7ced6354325b150c628633204970019a
+Subproject commit c6a478ddc4d8374e6d7ae02628be9a44d74889f7