[CodeHealth] Update outdated WebOTP proposal link

TBR=dcheng@chromium.org

Bug: None
Change-Id: Id34814442f8b763782eb70657de33b57a7e03617
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2375799
Commit-Queue: Yi Gu <yigu@chromium.org>
Reviewed-by: Reilly Grant <reillyg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#801754}

third_party/blink/public/mojom/sms/sms_receiver.mojom

@@ -8,7 +8,7 @@ import "mojo/public/mojom/base/time.mojom";
 
 // Implementation of the proposed "Sms Detection API".
 //
-// Proposal: https://github.com/samuelgoto/sms-receiver
+// Proposal: https://github.com/WICG/web-otp
 enum SmsStatus {
   kSuccess,
   kTimeout,