warehouse/templates: Deduplicate TOTP application guidance

Additionally, add Duo Mobile to the recommended list.

warehouse/templates/manage/account/totp-provision.html

@@ -35,11 +35,9 @@ <h2>How 2FA with TOTP works</h2>
 
   <h2>Provisioning your application</h2>
 
-  <p>You can provision any compatible TOTP application to generate two factor authentication codes for PyPI. We recommend <a href="https://play.google.com/store/apps/details?id=com.google.android.apps.authenticator2&hl=en_GB">Google Authenticator for Android</a> or <a href="https://itunes.apple.com/gb/app/google-authenticator/id388497605?mt=8">iPhone</a>, <a href="https://support.1password.com/one-time-passwords/">1Password</a>, <a href="https://authy.com/">Authy</a> or <a href="https://lastpass.com/auth/">LastPass Authenticator</a>.</p>
-
   <p>For security reasons, you should only provision one device/application at a time.</p>
 
-  <p><strong>Scan the QR code with your application of choice to provision the application:</strong></p>
+  <p><strong>Scan the QR code with your application of choice:</strong></p>
 
   <br>
   <img src="{{ request.route_path('manage.account.totp-provision.image') }}" aria-label="{{ provision_totp_uri }}">

warehouse/templates/pages/help.html

@@ -180,8 +180,9 @@ <h3 id="totp">{{ totp() }}</h3>
         <ul>
           <li><a href="https://freeotp.github.io/">FreeOTP</a> (open source)</li>
           <li><a href="https://play.google.com/store/apps/details?id=org.liberty.android.freeotpplus">FreeOTP+</a> (open source)</li>
-          <li>Google Authenticator for <a href="https://play.google.com/store/apps/details?id=com.google.android.apps.authenticator2">Android</a> or <a href="https://itunes.apple.com/gb/app/google-authenticator/id388497605?mt=8">iPhone</a> (proprietary)</li>
+          <li>Google Authenticator for <a href="https://play.google.com/store/apps/details?id=com.google.android.apps.authenticator2">Android</a> or <a href="https://itunes.apple.com/app/google-authenticator/id388497605">iPhone</a> (proprietary)</li>
           <li><a href="https://authy.com/">Authy</a> (proprietary)</li>
+          <li>Duo Mobile for <a href="https://play.google.com/store/apps/details?id=com.duosecurity.duomobile">Android</a> and <a href="https://itunes.apple.com/app/duo-mobile/id422663827">iPhone</a> (proprietary)</li>
         </ul>
         <p>Open the application of your choice to generate a code.</p>
       </section>