Update index.bs

Adjust the setup serviceworkerglobalscope algorithm name to
be aligned with the other naming rule.

Author: yoshisatoyanagisawa

docs/index.bs

@@ -2991,7 +2991,7 @@ spec: storage; urlPrefix: https://storage.spec.whatwg.org/
   </section>
 
   <section algorithm>
-    <h3 id="setup-serviceworkerglobalscope"><dfn>Setup ServiceWorkerGlobalScope</dfn></h3>
+    <h3 id="setup-serviceworkerglobalscope-algorithm"><dfn>Setup ServiceWorkerGlobalScope</dfn></h3>
 
       : Input
       :: |serviceWorker|, a [=/service worker=]