net/tlsdial: update package doc to say it's now somewhat useless

net/tlsdial/tlsdial.go

@@ -2,8 +2,13 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Package tlsdial sets up a tls.Config for x509 validation, using
-// a memory-optimized path for iOS.
+// Package tlsdial originally existed to set up a tls.Config for x509
+// validation, using a memory-optimized path for iOS, but then we
+// moved that to the tailscale/go tree instead, so now this package
+// does very little. But for now we keep it as a unified point where
+// we might want to add shared policy on outgoing TLS connections from
+// the 3 places in the client that connect to Tailscale (logs,
+// control, DERP).
 package tlsdial
 
 import "crypto/tls"