editorial: Adjust references in Permissions Policy section

* Remove `data-link-for="Navigator"`, unneeded since #42.
* Fix reference to "default allowlist", which has needed the
  "policy-controlled feature" scope since
  w3c/webappsec-permissions-policy#498. I could not get it to work using the
  `<a>` syntax with ReSpec though.
* While here, make "self" a reference to the corresponding term in the
  Permissions Policy spec.

index.html

@@ -561,10 +561,10 @@ <h2>
       <h2>
         Permissions Policy integration
       </h2>
-      <p data-link-for="Navigator">
+      <p>
         The Battery Status API is a <a>policy-controlled feature</a> identified
-        by the string "<code>battery</code>". Its <a>default allowlist</a> is
-        <code>'self'</code>.
+        by the string "<code>battery</code>". Its [=policy-controlled feature/default allowlist=]
+        is <code>[=default allowlist/'self'=]</code>.
       </p>
     </section>
     <section class="informative">