Ideally some of these templates should really point to the
local installation's support email address, but this is a
good start.
Exceptions:
* Where to report security incidents
* MIT Zephyr-related pages
* zulip.com terms and conditions
We use this error page for all 5xx errors, so I'm removing the error
number from the text.
(imported from commit c0c4c8829d466dd20c76dbbc920fc57cafbd6e6c)