caldav_sync: Added a note to the index.html page about app-specific passwords.

caldav_sync/static/description/index.html

@@ -44,6 +44,11 @@
             <li>Go to the User settings in Odoo.</li>
             <li>Enter the CalDAV calendar URL, username, and password on the user settings.</li>
         </ol>
+        <p><strong>Note: </strong>Some calendar service providers such as
+            Apple iCloud require app-specific passwords to be set so that
+            the calendar API can bypass 2-factor authentication. Please look
+        into setting up app-specific passwords for your cloud calendar
+            provider if you're faced with authentication errors.</p>
         <h2>Usage</h2>
         <ol>
             <li>Create a calendar event in Odoo and it will be synchronized with the CalDAV calendar.</li>