fix image shared with web share

src/views/SharedPhotoView.vue

@@ -48,6 +48,15 @@
     </div>
     <div v-else class="text-center mb-4">
       <p>No image found.</p>
+      <p class="mt-4">
+        If you shared an image, the cause is usually that you do not have the
+        recent version of this app, or that the app has not refreshed the
+        service code underneath. To fix this, first make sure you have latest
+        version by comparing your version at the bottom of "Help" with the
+        version at the bottom of https://timesafari.app/help in a browser. After
+        that, it may eventually work, but you can speed up the process by clearing
+        your data cache (in the browser on mobile, even if you installed it) and/or
+        reinstalling the app (after backing up all your data, of course).</p>
     </div>
   </section>
 </template>