Update FAQ

FAQ.md

@@ -606,6 +606,8 @@ This can be caused by using an incorrect host name, so first double-check the ho
 Please see the documentation of the email provider about the right host name.
 Sometimes the right host name is in the error message.
 
+Another possible cause is [Certificate transparency](https://github.com/appmattus/certificatetransparency) failing, so try disabling it in the connection settings tab page.
+
 You should try to fix this by contacting your provider or by getting a valid security certificate
 because invalid security certificates are insecure and allow [man-in-the-middle attacks](https://en.wikipedia.org/wiki/Man-in-the-middle_attack).
 If money is an obstacle, you can get free security certificates from [Let’s Encrypt](https://letsencrypt.org).

index.html

@@ -552,6 +552,7 @@ Therefore, this issue can only be resolved by your email provider,
 or by installing the GitHub version of the app (as an update) and enabling insecure connections in the account/identity settings.** -->
 <p><em>… Untrusted … not in certificate …</em><br /> <em>… Invalid security certificate (Can’t verify identity of server) …</em><br /> <em>… Chain validation failed … timestamp check failed … Certificate expired at …</em><br /></p>
 <p>This can be caused by using an incorrect host name, so first double-check the host name in the advanced identity/account settings (tap <em>Manual setup and account options</em>). Please see the documentation of the email provider about the right host name. Sometimes the right host name is in the error message.</p>
+<p>Another possible cause is <a href="https://github.com/appmattus/certificatetransparency">Certificate transparency</a> failing, so try disabling it in the connection settings tab page.</p>
 <p>You should try to fix this by contacting your provider or by getting a valid security certificate because invalid security certificates are insecure and allow <a href="https://en.wikipedia.org/wiki/Man-in-the-middle_attack">man-in-the-middle attacks</a>. If money is an obstacle, you can get free security certificates from <a href="https://letsencrypt.org">Let’s Encrypt</a>.</p>
 <p>The quick, but unsafe solution (not advised), is to enable <em>Insecure connections</em> in the advanced identity settings (navigation menu, tap <em>Settings</em>, tap <em>Manual setup</em>, tap <em>Identities</em>, tap the identity, tap <em>Advanced</em>).</p>
 <p>Alternatively, you can accept the fingerprint of invalid server certificates like this:</p>