add correct encodings for public keys, plus some instructions for entering a contact

src/views/HelpView.vue

@@ -134,6 +134,18 @@
           <li>Make sure you have your backup file (above), then contact us.</li>
         </ul>
       </div>
+
+      <h2 class="text-xl font-semibold">
+        How do I add someone to my contacts?
+      </h2>
+      <p>
+        Tell them to copy their ID, which typically starts with "did:ethr:...",
+        and send it to you. Go to the Contacts
+        <fa icon="circle-user" class="fa-fw" /> page and enter that into the top
+        form. You may add a name by adding a comma followed by their name; you
+        may also add their public key by adding another comma followed by the
+        key.
+      </p>
     </div>
   </section>
 </template>