for both 7.12 and master, this page on our main elastic site has a broken link, from Beats repo docs:
https://www.elastic.co/guide/en/beats/libbeat/current/beats-reference.html

That URL maps to this:
https://github.com/elastic/beats/blob/master/libbeat/docs/overview.asciidoc

and in this... the link for packetbeat is broken. The file doesn't exist so it throws a 500 error.
The link points to:
https://www.elastic.co/products/beats/packetbeat

where I believe want it to resole to:
https://www.elastic.co/downloads/beats/packetbeat

I'm sure it is a short-link or otherwise dynamically controlled so I'm not sure who owns that or where it is etc.