download.html is 404 and renders weird

[bishabosha]

/download.html now 404's and has moved to /download which breaks links.

https://www.scala-sbt.org/download.html

However weirdly the page seems to still render /download after the page footer:

[bishabosha]

unfortunately it seems this did not solve it on the GitHub pages side - I think we actually need to generate html pages wherever there are these slug fields

[bishabosha]

the second PR worked, so
fixed by #1183