markdown-include is GPL licensed.
Also, rewrite it as a block processor, so that it works correctly
inside indented blocks.
Signed-off-by: Anders Kaseorg <anders@zulip.com>
I have updated the documentation for the Zabbix integration to give the
correct instructions for the latest version of Zabbix (5.2). The old
instructions are now obsolete.
I have also updated the message that is PMd to a user if the webhook
doesn't receive a complete payload to also align with the new
instructions.