polished up TOTP enrolment

admin/views/totp-confirm.html

@@ -19,6 +19,7 @@ code {
     {{end}}
 
     <form action="/admin/account/totp-confirm?totp-name={{.NameEscaped}}" method="POST" id="totp-setup">
+        {{if .QRBase64Image}}
         <img src="data:image/png;base64,{{.QRBase64Image}}" alt="" class="qr-code">
 
         <p>
@@ -29,6 +30,12 @@ code {
         <p>
         If the QR code does not work, you may also enter this secret code:
         </p>
+        {{else}}
+        <p>
+        Paste the below secret code into your authentication app or password manager,
+        then enter your 2FA code below:
+        </p>
+        {{end}}
 
         <p><code>{{.TOTP.Secret}}</code></p>