[link-validator] Missing file context-api.md

Hello,

There is a note, with a broken reference link.

| Note: This command lets automation verify that the
|    [context api](https://github.com/fedidcg/FedCM/blob/main/proposals/context-api.md)
|    was applied properly

I searched inside the repo and could not find it.

I am proposing to remove it or feel free to modify the PR.

Thanks,

Simone

P.S. this should be the last check for publication in `/TR`

spec/index.bs

@@ -2412,10 +2412,6 @@ The [=remote end steps=] are:
     </table>
 </figure>
 
-Note: This command lets automation verify that the
-    [context api](https://github.com/fedidcg/FedCM/blob/main/proposals/context-api.md)
-    was applied properly
-
 The [=remote end steps=] are:
 
 1. If no FedCM dialog is currently open, return a [=error|WebDriver error=] with