all: add test for package comments, fix, add comments as needed

Updates #cleanup

Change-Id: Ic4304e909d2131a95a38b26911f49e7b1729aaef
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

util/limiter/limiter.go

@@ -1,6 +1,7 @@
 // Copyright (c) Tailscale Inc & AUTHORS
 // SPDX-License-Identifier: BSD-3-Clause
 
+// Package limiter provides a keyed token bucket rate limiter.
 package limiter
 
 import (

util/linuxfw/linuxfw.go

@@ -1,10 +1,9 @@
 // Copyright (c) Tailscale Inc & AUTHORS
 // SPDX-License-Identifier: BSD-3-Clause
 
-// Package linuxfw returns the kind of firewall being used by the kernel.
-
 //go:build linux
 
+// Package linuxfw returns the kind of firewall being used by the kernel.
 package linuxfw
 
 import (

util/osdiag/internal/wsc/wsc_windows.go

@@ -3,6 +3,7 @@
 
 // Code generated by 'go generate'; DO NOT EDIT.
 
+// Package wsc provides access to the Windows Security Center API.
 package wsc
 
 import (

util/osshare/filesharingstatus_windows.go

@@ -1,8 +1,8 @@
 // Copyright (c) Tailscale Inc & AUTHORS
 // SPDX-License-Identifier: BSD-3-Clause
 
-//go:build windows
-
+// Package osshare provides utilities for enabling/disabling Taildrop file
+// sharing on Windows.
 package osshare
 
 import (

util/winutil/authenticode/authenticode_windows.go

@@ -1,6 +1,7 @@
 // Copyright (c) Tailscale Inc & AUTHORS
 // SPDX-License-Identifier: BSD-3-Clause
 
+// Package authenticode contains Windows Authenticode signature verification code.
 package authenticode
 
 import (

util/winutil/testdata/testrestartableprocesses/restartableprocess_windows.go

@@ -1,6 +1,7 @@
 // Copyright (c) Tailscale Inc & AUTHORS
 // SPDX-License-Identifier: BSD-3-Clause
 
+// The testrestartableprocesses is a program for a test.
 package main
 
 import (

util/winutil/winenv/mksyscall.go

@@ -1,5 +1,6 @@
 // Copyright (c) Tailscale Inc & AUTHORS
 // SPDX-License-Identifier: BSD-3-Clause
+
 package winenv
 
 //go:generate go run golang.org/x/sys/windows/mkwinsyscall -output zsyscall_windows.go mksyscall.go