Minor fix to example for simple verifiable profile.

Author: msporny

index.html

@@ -1300,6 +1300,10 @@ <h2>Verifiable Profile</h2>
       simple <a>verifiable profile</a>.</p>
 
 <pre class="example" title="A simple verifiable profile">{
+  "@context": [
+    "https://w3id.org/identity/v1",
+    "https://w3id.org/security/v1"
+  ],
   "id": "did:example:ebfeb1f712ebc6f1c276e12ec21",
   "credential": [{
     "id": "http://dmv.example.gov/credentials/3732",