time/tzdata: update links in comment

Change-Id: I141d29bb4adc957de5de1f8ed8867980fd3c8386
Reviewed-on: https://go-review.googlesource.com/c/go/+/342071
Trust: Ian Lance Taylor <[email protected]>
Run-TryBot: Ian Lance Taylor <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Reviewed-by: Emmanuel Odeke <[email protected]>

Author: ianlancetaylor

src/time/tzdata/generate_zipdata.go

@@ -31,8 +31,8 @@ const header = `// Copyright 2020 The Go Authors. All rights reserved.
 
 // For more information, see
 // https://www.iana.org/time-zones
-// ftp://ftp.iana.org/tz/code/tz-link.htm
-// http://tools.ietf.org/html/rfc6557
+// ftp://ftp.iana.org/tz/code/tz-link.html
+// https://datatracker.ietf.org/doc/html/rfc6557
 
 package tzdata