Web UI: keep Firefox from autofilling the new admin password

Firefox filled a saved login into the System tab's password fields and
its user name into the NTP poll interval, the input before them. That
input event marked the Time card as edited, so ntpLoad() left NTP off,
the server empty and the time zone at UTC-12:00.

CHANGELOG.md

@@ -26,6 +26,9 @@
 ## Fixed
 
 - Web UI
+  - Firefox no longer fills a saved login into the new admin password fields. It also put the
+    user name into the NTP poll interval, which marked the Time card as edited, so it kept its
+    defaults (NTP off, no server, UTC-12:00) instead of the switch's settings.
   - Accept firmware uploads regardless of the file part's MIME type, including
     `application/macbinary` sent by Chrome on macOS for `.bin` files.