automatically create an identity on the first page (and other UI tweaks)

src/views/HelpView.vue

@@ -69,6 +69,18 @@
         make it an opportunity to get to know their projects, and show your own.
       </p>
 
+      <h2 class="text-xl font-semibold">
+        I had an identifier, but I reinstalled and I got a new one automatically.
+        How do I restore my old one?
+      </h2>
+      <p>
+        Go to the page
+        <router-link class="text-blue-500" to="/import-account">import your identifier</router-link>.
+        If you don't want the old one, click "Advanced" and check the box to erase it.
+        (The erase option only shows if you have exactly one identifier.
+         For more in-depth surgery, you'll have to erase data from the browser or reinstall.)
+      </p>
+
       <h2 class="text-xl font-semibold">How do I add someone else?</h2>
       <p>
         <button class="text-blue-500" @click="showOnboardInfo">