Update fetch.bs

Co-authored-by: Anne van Kesteren <[email protected]>

Author: noamr

fetch.bs

@@ -6911,7 +6911,7 @@ throw.
 </code></pre>
 
 <p>Same-origin nested documents share the quota of their parent. However, cross-origin or
-cross-agent iframes only receive 8kb of quota by default. So in the following example, the first 3
+cross-agent iframes only receive 8kb of quota by default. So in the following example, the first three
 calls would succeed and the last one would throw.
 <pre><code class=lang-javascript>
   // In main page