Hello Dirk,
thanks for the information.
within the current description, the link of interest to me (below “Core Modules” → “Icinga Powershell Framework”) leads to exactly the same non-existent page… https://icinga.com/docs/windows/latest/doc/02-Installation/
The link in the description is just a leftover, because the url structure of the docs changed. The page Dirk directed you to is the correct one (the Icinga docs).
I am submitting a pull request on GitHub for it, you could always do that yourself too though if you find something like that again