docs: Enable all missing module docs

Change-Id: I9a1f575bf3eb1152c16920f147e160857abbcb3f
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/45082
Reviewed-by: Armando Montanez <amontanez@google.com>
Reviewed-by: Keir Mierle <keir@google.com>
Pigweed-Auto-Submit: Ewout van Bekkum <ewout@google.com>
Commit-Queue: Auto-Submit <auto-submit@pigweed.google.com.iam.gserviceaccount.com>