[LNA] Update urls for spec location

Change links pointing to the LNA explainer to point to the LNA spec
instead.

Also remove a random TODO that was already done that was next to
one of the links.

Bug: 394009026
Change-Id: I4194fe973c1aeec924b797ec8cabbffed2bcc705
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6768252
Reviewed-by: Adam Rice <ricea@chromium.org>
Reviewed-by: Igor Ruvinov <igorruvinov@chromium.org>
Commit-Queue: Hubert Chao <hchao@chromium.org>
Reviewed-by: Chris Thompson <cthomp@chromium.org>
Reviewed-by: Giovanni Ortuno Urquidi <ortuno@chromium.org>
Reviewed-by: Andrey Kosyakov <caseq@chromium.org>
Reviewed-by: Camille Lamy <clamy@chromium.org>
Reviewed-by: Yann Dago <ydago@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1491156}

Author: hubertchao

fetch/local-network-access/README.md

@@ -5,7 +5,7 @@ the Fetch specification.
 
 See also:
 
-* [Explainer](https://github.com/explainers-by-googlers/local-network-access)
+* [Spec](https://wicg.github.io/local-network-access/)
 
 Local Network Access replaced [Private Network
-Access](https://wicg.github.io/local-network-access/).
+Access](https://wicg.github.io/private-network-access/).