Update add device instructions (#1016)

* Update add device instructions

The flow changed a little but the text wasn't updated.

* Remove 'and then'

* 🤖 Selenium screenshots auto-update

Co-authored-by: github-actions <41898282+github-actions[bot]@users.noreply.github.com>

Author: nmattia

screenshots/desktop/renderPollForTentativeDevicePage.png

@@ -27,10 +27,9 @@ const pageContent = (userNumber: bigint) => html`
       </li>
       <li>
         On your <em>new</em> device:<br />
-        Chose
-        <strong class="t-strong"
-          >Already have an anchor but using a new device?</strong
-        >
+        Chose <strong class="t-strong">Add a Device</strong> (if you don't see
+        the option, click on
+        <strong class="t-strong">Use Existing</strong> first)
       </li>
       <li>
         On your <em>new</em> device:<br />

screenshots/mobile/renderPollForTentativeDevicePage.png

@@ -46,7 +46,7 @@ const pageContent = (connection: Connection, userNumber?: bigint) => {
 };
 
 /**
- * Entry point for the flow of adding a new authenticator when starting from the welcome view (by clicking 'Already have an anchor but using a new device?').
+ * Entry point for the flow of adding a new authenticator when starting from landing page.
  * This shows a prompt to enter the identity anchor to add this new device to.
  */
 export const addRemoteDevice = (