Update index.html

Co-authored-by: Michael B. Jones <[email protected]>

index.html

@@ -1185,7 +1185,7 @@ <h2>Securing Verifiable Credentials</h2>
       </p>
       <p>
         The JWT Claim Names <code>vc</code> and <code>vp</code>
-        MUST NOT be present in any JWT Claim Set.
+        MUST NOT be present in any JWT Claims Set.
       </p>
     </section>